Hi all,

I have one Custom object CaseType__c which has some custom fields like CaseTypeName, CaseTypeDescription etc and one look up relation of another object Specimen__c which has also some fields like SpecimenName, SpeimentType, SpecimenDescription like that. On VF page I have loaded the CaeTypeName as picklist from CaseTypeObject by ApexCode.

Now my requirment is on the selection of particular CaseTypeName__c, all the fields of Specimen object like SpecimentName, SpecimenType SpecimenDescription should be come. Like If CaseTypeName -ABC has Specimen BCD than on the selection of CaseType-ABC all the fields of Specimen related to BCD record should display on VF page.

This is code but not working ,, please please help, I have ried much but did not get anything

<apex:page controller="ExtentionController"

extensions="CaseTypeExtention">
    <apex:form >
          <apex:pageblock title="Hello {!$User.FirstName}!" >
              <h1>Congratulations</h1>
              This is your Accession Page !!<p/>

 <apex:pageBlockSection title="Case Information" >
                   <apex:selectList value="{!objCaseType.CaseTypeName__c }" size="1" multiselect="false">
                    <apex:actionSupport event="onchange" reRender="details" action="{!readSpecimen}"/>
                        <apex:selectOptions Value="{!CaseTypeOption }">
                        </apex:selectOptions>
                        </apex:selectList>
                 </apex:pageblocksection>
            
                  <apex:pageBlockSection title="Specimen" id="details">
                        <apex:pageBlockTable value="{!SpecimenList}" var="spec"   border="red" width="500%"  >
                            <apex:column value="{!SpecimenList.Name}" width="100%"/>
                            <apex:column value="{!SpecimenList.SpecimenType__c}" width="100%"/>
                        </apex:pageBlockTable>
                    </apex:pageblocksection> 

  </apex:pageblock>
      </apex:form>

</apex:page>

Apex Code

public class CaseTypeExtention
  {
        public CaseType__c objCaseType {get;set;}
       
        public Specimen__c SpecimenList  {get;set;}
        //public List<CaseType__c> caseList {get; set;}
       
        public CaseTypeExtention(ExtentionController controller)
         {
                objCaseType = new CaseType__c();
                SpecimenList = new Specimen__c();
               // caseList  = new List<CaseType__c>();
         }
        public List<selectOption> CaseTypeOption
        {
            get
            {
                List<selectOption> CaseTypeName =new List<selectOption>();
               
                CaseTypeName.add(new selectOption('None', 'None'));
               
                for (CaseType__c cn :[select  Name , CaseTypeName__c from CaseType__c])
               
                CaseTypeName.add(new selectOption(cn.Name, cn.CaseTypeName__c));
                return CaseTypeName;
            }
            private set;
        }
                                   
        public PageReference readSpecimen()
        {
            //caseList  = [Select  Specimen__c From CaseType__c Where name = '000002' limit 1 ];
            //string specimenId = caseList.Specimen__c;
           
            SpecimenList   = [select  name, SpecimenType__c from Specimen__c where id=:objCaseType.Specimen__c ];
            return null;
        }
 }