[SalesForce] System.QueryException: unexpected token: ‘‘

I have built dynamic query.but receiving below exception

 01:16:56.0 (15683245)|USER_DEBUG|[335]|DEBUG|SetOfParentId--->{}
  01:16:56.0 (15756602)|USER_DEBUG|[336]|DEBUG|Set1--->{}
  01:16:56.0 (15788512)|USER_DEBUG|[337]|DEBUG|SetOfGSSDuplicateCase--->{}
  01:16:56.0 (15816995)|USER_DEBUG|[338]|DEBUG|Set11--->{}
  01:16:56.0 (15864603)|USER_DEBUG|[404]|DEBUG|soqlString---->select id,Vmstar_Id__c,GSS_Duplicate_Case__c,Duplicate_Of_Case__c,GSS_Build_Number__c, 
   GSS_Product_Version__c from Case Where 
      01:16:56.0 (16227040)|EXCEPTION_THROWN|[405]|System.QueryException: 
         unexpected token: '<EOF>'
             01:16:56.0 (16357113)|FATAL_ERROR|System.QueryException: 
          unexpected token: '<EOF>'


**Dynamic query:**


 string soqlString = 'select id,Vmstar_Id__c,GSS_Duplicate_Case__c,Duplicate_Of_Case__c,GSS_Build_Number__c,GSS_Product_Version__c from Case';
        soqlString += ' Where '; 
        boolean whereClauseAdded = false;
        if(SetOfParentId.size()>0){
            whereClauseAdded = true;
            soqlString += ' Vmstar_Id__c IN : SetOfParentId';
        }
        if(SetOfGSSDuplicateCase.size()>0){
            if(whereClauseAdded)
                soqlString += ' OR Vmstar_Id__c IN : SetOfGSSDuplicateCase';
            else 
                soqlString += ' Vmstar_Id__c IN : SetOfGSSDuplicateCase';

            whereClauseAdded = true;
        }
        if(Set1.size()>0 ){

            if(whereClauseAdded)
                soqlString += ' OR GSS_Build_Number__c IN :  Set1';
            else 
                soqlString += ' GSS_Build_Number__c IN :  Set1';

            whereClauseAdded = true;


        }
        if(Set11.size()>0){

            if(whereClauseAdded)
                soqlString += ' OR GSS_Product_Version__c  IN : Set11';
            else 
                soqlString += ' GSS_Product_Version__c  IN : Set11';

            whereClauseAdded = true;
             }

        system.debug('soqlString---->'+soqlString);
        List<Case> requiredCases = Database.query(soqlString);


        if(requiredCases.size()>0){

        for(Case et : requiredCases){

            if(et.id!=null){
                MapOfParentId.put(et.Vmstar_Id__c,et.id);
            }if(et.GSS_Duplicate_Case__c!=null){
                MapOfGSSDuplicateCase.put(et.VMstar_Id__c,et.GSS_Duplicate_Case__c);              
            }if(et.Duplicate_Of_Case__c!=null){
                MapOfDuplicateOfCase.put(et.VMstar_Id__c,et.Duplicate_Of_Case__c);
            }if(et.GSS_Build_Number__c!=null){
                Set3.add(et.GSS_Build_Number__c);
            }if(et.GSS_Product_Version__c!=null){
                Set33.add(et.GSS_Build_Number__c);
            }

          }  
        }