"HttpSendRequest" failed, Windows error code=12002 - Perf Center Error

Hi All,
I am doing perf testing for one of our internal web application. I can run the created script successfully in VuGen (9.52) but performance center (9.5) throws following errors:
 
Action.c(1288): Error -27492: "HttpSendRequest" failed, Windows error code=12002 and retry limit (0) exceeded for URL="https://xxx/yyy/zzz/aaa/bbb/cccc/portfolio_performance.do?", Snapshot Info
Action.c(52): Error -27492: "HttpSendRequest" failed, Windows error code=12002 and retry limit (0) exceeded for URL="https:/xxx/yyyy/zzzz/homePage.do", Snapshot Info [MSH 0 1]
There are so many errors like above which point towards diff. URLs. I am trying to reach to 30 vusers but i am seeing errors occurring sometime at 10 users or 15 or sometime 21 users. I am using 1 LG.
FYI, i am using WinInet replay engine as default win-socket throws 401 error (even with web_set_user function) because of some secured JAVA applets. I can't even turn off window's integrated Auth, as that gives exception errors.  
If anybody has faced this error, please guide me. 
Thanks,
Krunal