I am using NFUSE Script ( CITRIX + HTTP ) and the script runs perfect in VUgen. Now when I run the script in Controller with 35 Concurrent VUsers then 15 Pass and 20 Fail.

I get an error ctrx_sync_on_windows() -- expected window cannot be displayed.

Now what baffles me is all VUsers should have their own session to work on so why is the case that same script works for 1 Vuser and fails for the other ?