Hi All,

I have a custom picklist field that is Courses which has some drop down values like Salesforce,Java, SAP etc. and the same field in three tabs.
In 3rd Tab, when i select value like SAP then it goes to controller and did some actions.-- its working fine.

1st and 2nd Tab, when i select same value SAP then not passing any values to controller and every time it takes value like '---select course---'  in debug log.

And i observed one thing in Debug Log, Internally it takes value which i select from VF page and sets. Again the value is changed as ---Select Course---. 
My Page:

<apex:page standardController="Contact" extensions="RunningBatchController" id="pg">
    <apex:form id="frm">
        <apex:tabPanel switchType="client" selectedTab="name1" id="theTabPanel">
        <apex:tab label="Running Batch Information" name="name1" id="tabOne" title="Running Batch">
            <apex:pageBlock title="Running Batch ">
                <apex:pageBlockSection title="Batch Information" columns="1">
                <apex:selectlist value="{!selectedCourse}" size="1" id="rc" label="Course Name: "> 
                    <apex:SelectOptions value="{!CourseList}" />  
                  <!--  <apex:actionSupport event="onchange" id="rpbt"/> -->   
                </apex:selectlist>
        
            <apex:pageBlockSectionItem >
            <apex:outputLabel value="Batch No:"/>
            <apex:inputField value="{!contact.Batch_No__c}"/>
            </apex:pageBlockSectionItem>
        </apex:pageBlockSection>
        <apex:pageBlockButtons >
            <apex:commandButton value="Search" action="{!searchBatches}" id="rbtn" reRender="rpbt"/>
        </apex:pageBlockButtons>
      <!--  <apex:pageBlockSection >-->
            <apex:pageBlockTable value="{!studentsList}" var="s" id="rpbt">
                <apex:column value="{!s.Name}"/>
                <apex:column value="{!s.Course__r.name}"/>
                <apex:column value="{!s.Batch_No__c}"/>
                <apex:column value="{!s.staff__c}"/>
                <apex:column value="{!s.MobilePhone}"/>
                <apex:column value="{!s.email}"/>
                <apex:column value="{!s.Status__c}"/>
            </apex:pageBlockTable>
     <!--   </apex:pageBlockSection>-->
    </apex:pageBlock>
    </apex:tab>
    
    
    <apex:tab label="Pending Batch Information" name="name2" id="tabTwo" title="Pending Batch">
            <apex:pageBlock title="Pending Batch ">
                <apex:pageBlockSection title="Batch Information" columns="1" id="pbs2">
                <apex:selectlist value="{!selectedCourse}" size="1" id="pc" label="Course Name: "> 
                    <apex:SelectOptions value="{!CourseList}"/>  
                    <apex:actionSupport event="onchange" reRender="ppbt"/>    
                </apex:selectlist>
                 
        </apex:pageBlockSection>
        <apex:pageBlockButtons >
            <apex:commandButton value="Search" action="{!searchPendingBatches}" id="btn" reRender="ppbt"/>
        </apex:pageBlockButtons>
      <!--  <apex:pageBlockSection >-->
            <apex:pageBlockTable value="{!studentsList}" var="s" id="ppbt">
                <apex:column value="{!s.Name}"/>
                <apex:column value="{!s.Course__r.name}"/>
                <apex:column value="{!s.Batch_No__c}"/>
                <apex:column value="{!s.staff__c}"/>
                <apex:column value="{!s.MobilePhone}"/>
                <apex:column value="{!s.email}"/>
                <apex:column value="{!s.Status__c}"/>
            </apex:pageBlockTable>
      <!--   </apex:pageBlockSection>-->
    </apex:pageBlock>
    </apex:tab>
    
    <apex:tab label="Completed Batch Information" name="name3" id="tabThree" title="Completed batch">
            <apex:pageBlock title="Completed Batch ">
                <apex:pageBlockSection title="Batch Information" columns="1" id="pbs3">
                <apex:selectlist value="{!selectedCourse}" size="1" id="cc" label="Course Name: ">
                     
                    <apex:SelectOptions value="{!CourseList}"/> 
                  <!--  <apex:actionSupport event="onchange" reRender="cpbt"/> -->   
                </apex:selectlist>
                 
        </apex:pageBlockSection>
        <apex:pageBlockButtons >
            <apex:commandButton value="Search" action="{!searchCompletedBatches}" id="Cbtn" reRender="cpbt"/>
        </apex:pageBlockButtons>
      <!--  <apex:pageBlockSection >-->
            <apex:pageBlockTable value="{!studentsList}" var="s" id="cpbt">
                <apex:column value="{!s.Name}"/>
                <apex:column value="{!s.Course__r.name}"/>
                <apex:column value="{!s.Batch_No__c}"/>
                <apex:column value="{!s.staff__c}"/>
                <apex:column value="{!s.MobilePhone}"/>
                <apex:column value="{!s.email}"/>
                <apex:column value="{!s.Status__c}"/>
            </apex:pageBlockTable>
      <!--   </apex:pageBlockSection>-->
    </apex:pageBlock>
    </apex:tab>
    
    </apex:tabPanel>
    </apex:form>
</apex:page>

​Controller:
public with sharing class RunningBatchController{
    
    public String selectedCourse { get; set; }
    public List<Contact> studentsList{get;set;}  
    
    public ApexPages.StandardController controller{get;set;}
    public RunningBatchController(ApexPages.StandardController controller) {
        this.controller = controller;
        system.debug('ddd '+controller);
        
    }

    public List<SelectOption> getCourseList(){
        
        List<SelectOption> CourseList = new List<SelectOption>();
        
        CourseList.add(new SelectOption('------- Select Course -------','------- Select Course -------')); 
        List<Product2> prodList = [Select id, Name from Product2];
        for(Product2 pc :prodList){
            CourseList.add(new SelectOption(pc.Id,pc.Name));     
        }
       return CourseList;    
    }
    
    
    
    
    
    public void searchBatches(){
        
        Contact bch = (Contact)controller.getRecord();
       system.debug('course '+selectedCourse);
       system.debug('batch '+bch.Batch_No__c);
      // String course = bch.Course__c;
       String batch = bch.Batch_No__c;
       
       if(selectedCourse != '------- Select Course -------' && batch != '--None--'){
           studentsList = [select id,Name,course__c,Course__r.name,Batch_No__c,Staff__c,MobilePhone,Status__c,Email from Contact where course__c =: selectedCourse and Batch_No__c =: batch and Status__c ='Active'];
        }else if(selectedCourse != '------- Select Course -------' && batch == '--None--'){
            studentsList = [select id,Name,course__c,Course__r.name,Batch_No__c,Staff__c,MobilePhone,Status__c,Email from Contact where course__c =: selectedCourse and Status__c ='Active'];
        }else{
            studentsList = [select id,Name,course__c,Course__r.name,Batch_No__c,Staff__c,MobilePhone,Status__c,Email from Contact where Status__c ='Active'];
        }
    }
    
    public void searchPendingBatches(){
        
        Contact bch = (Contact)controller.getRecord();
      system.debug('ppppp '+selectedCourse);
            
      if(selectedCourse == '------- Select Course -------'){
          system.debug('nothing ');
          studentsList = [select id,Name,course__c,Course__r.name,Batch_No__c,Staff__c,MobilePhone,Status__c,Email from Contact where Status__c ='Pending'];        
      }else{
          system.debug('selected course');
          studentsList = [select id,Name,course__c,Course__r.name,Batch_No__c,Staff__c,MobilePhone,Status__c,Email from Contact where course__c =: selectedCourse and Status__c ='Pending'];
        }
      
    }
    
    public void searchCompletedBatches(){
            
        Contact bch = (Contact)controller.getRecord();
                
       system.debug('cccc '+selectedCourse);
      if(selectedCourse == '------- Select Course -------'){
          system.debug('##');     
           studentsList = [select id,Name,course__c,Course__r.name,Batch_No__c,Staff__c,MobilePhone,Status__c,Email from Contact where Status__c ='In Active'];
           system.debug('@@'+studentsList.size());
      }else{
          system.debug('hii');
          studentsList = [select id,Name,course__c,Course__r.name,Batch_No__c,Staff__c,MobilePhone,Status__c,Email from Contact where course__c =: selectedCourse and Status__c ='In Active'];
        }
      
    }
    
}

 Debug Log:


Please anyone help me with appropriate solution.

I appriciate your response.

Thank You
Rakesh.