Performance Testing with Load Open UI

We are executing performance testing with HP load runner for Siebel IP15.14 application.Scripts are passing data accurately for search transactions when executed with single user.

When the load is increased to 15 or 20 a null query is being triggered in the back end nullifying the test data passed in search criteria.

Performance test center screen shot shows the data is passed as input but the siebel query in OM log does not have the input criteria leading into full table scan occupying maximum temp space.Example: Searching by Service Request number in UI during load test,where,OM log shows the null query without SR # condition in where clause.