Ajax truclient Firefox- Vugen 11 - Transaction not failed on object not found error

Hi,

We have developed a script in HP LoadRunner Vugen 11 using Ajax Truclient protocol. When we run the script in performance center we can see error message "targer object not found" there but it is not failing transaction.

So in results failed transaction = 0 and errors = 20 (for eg.)

Performance center version - 11.0

Please reply if there is any setting needs to be done in Step options.

Thanks in advance.