Internal Server Error (Http 500)

Hi,

I have recorded my script with VuGen which is a search senario. When I have replayed the scenario, it gave internal server error for "http://egitim.gocnet.gov.tr/Kullanici/Ara/Ara" . This is a ajax call function. It calls "Ara"  post function on Kullanici/Ara page. This url has been recorded when I clicked "Search" button on  Kullanici/Ara page.

On webpage,  I have replayed all scenario steps in manual and they are all successfull but when I haved replayed scenario, Vugen could not find this function. Also, while I am replaying this step, I have looked post function on browser's network with develeoper tools. Body part of this post function is same with Vugen record. 

Is there anyonewho can help me?

Here is the log:

Action.c(162): Error -26612: HTTP Status-Code=500 (Internal Server Error) for "http://egitim.gocnet.gov.tr/Kullanici/Ara/Ara"  [MsgId: MERR-26612]

And my script is attached.

Thanks,

Sinem.