I have created a page for dynamic search using Using jeffdouglas blog wit hsome modifications. Its not working form me. Am i wrong Anywhere?

CLASS:

public with sharing class vki2{

 private String soql {get;set;}
 
  public List<Contact> contacts {get;set;}

 
  public String sortDir {
    get  { if (sortDir == null) {  sortDir = 'desc'; } return sortDir;  }
    set;
  }

 
  public String sortField {
    get  { if (sortField == null) {sortField = 'Name'; } return sortField;  }
    set;
  }

 
  public String debugSoql {
    get { return soql + ' order by ' + sortField + ' ' + sortDir; }
    set;
  }

 
  public vki2() {
    soql = 'select Name, Leadsource from contact';
    runQuery();
  }

 
  public void toggleSort() {
    
    sortDir = sortDir.equals('asc') ? 'desc' : 'asc';
   
    runQuery();
  }

 
  public void runQuery() {

    try {
      contacts = Database.query(soql + ' order by ' + sortField + ' ' + sortDir);
    } catch (Exception e) {
      ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.ERROR, 'Oops!'));
    }

  }

    public PageReference runSearch() {

    String Name= Apexpages.currentPage().getParameters().get('Name');
     String Leadsource= Apexpages.currentPage().getParameters().get('Leadsource');
    
    soql = 'select Name,Leadsource from contact';
    
    if (!Name.equals(''))
      soql +=  ' and Name LIKE \''+String.escapeSingleQuotes(Name)+'%\'';
       if (!Leadsource.equals(''))
      soql += ' and Leadsource LIKE \''+String.escapeSingleQuotes(Leadsource)+'%\'';
  
    runQuery();

    return null;
  }

 
  public List<String> Leadsource{
    get {
      if (Leadsource== null) {

        Leadsource= new List<String>();
        Schema.DescribeFieldResult field = Contact.Leadsource.getDescribe();

        for (Schema.PicklistEntry f : field.getPicklistValues())
          Leadsource.add(f.getLabel());

      }
      return Leadsource;          
    }
    set;
  }

}


VF:

<apex:page controller="vki2" sidebar="false">
  <apex:form >
  <apex:pageMessages id="errors" />
  <apex:pageBlock title="Find!" mode="edit">
  <table width="100%" border="0">
  <tr>  
    <td width="200" valign="top">
      <apex:pageBlock title="Parameters" mode="edit" id="criteria">
      <script type="text/javascript">
      function doSearch() {
        searchServer(
          document.getElementById("Name").value,
         
          document.getElementById("Leadsource").options[document.getElementById("Leadsource").selectedIndex].value
          );
      }
      </script>
      <apex:actionFunction name="searchServer" action="{!runSearch}" rerender="results,debug,errors">
          <apex:param name="Name" value="" />
          <apex:param name="Leadsource" value="" />
      </apex:actionFunction>
      <table cellpadding="2" cellspacing="2">
      <tr>
        <td style="font-weight:bold;">Name<br/>
        <input type="text" id="Name" onkeyup="doSearch();"/>
        </td>
      </tr>
      <tr>
        <td style="font-weight:bold;">Leadsource<br/>
          <select id="leadsource" onchange="doSearch();">
            <option value=""></option>
            <apex:repeat value="{!Leadsource}" var="category">
              <option value="{!category}">{!category}</option>
            </apex:repeat>
          </select>
        </td>
      </tr>
      </table>
      </apex:pageBlock>
    </td>
    <td valign="top">
    <apex:pageBlock mode="edit" id="results">
        <apex:pageBlockTable value="{!contacts}" var="o">
            <apex:column >
                <apex:facet name="header">
                    <apex:commandLink value="Name" action="{!toggleSort}" rerender="results,debug">
                        <apex:param name="sortField" value="Name" assignTo="{!sortField}"/>
                    </apex:commandLink>
                </apex:facet>
                <apex:outputField value="{!o.Name}"/>
            </apex:column>
            <apex:column >
                <apex:facet name="header">
                    <apex:commandLink value="Leadsource" action="{!toggleSort}" rerender="results,debug">
                        <apex:param name="sortField" value="Leadsource" assignTo="{!sortField}"/>
                    </apex:commandLink>
                </apex:facet>
                <apex:outputField value="{!o.Leadsource}"/>
            </apex:column>
        </apex:pageBlockTable>
    </apex:pageBlock>
    </td>
  </tr>
  </table>
  </apex:pageBlock>
  </apex:form>
</apex:page>

Thank U