What language are you using?
in VB.net, the ^ operator raises the int on the left to the power on the right. The number is not infinity as google suggests, but is very large:
in VB.net, the maximum value of an int is: 2,147,483,647 (which is infinitely less than infinity)
Try this:
Clerk.Tasks.PutHandsUp(999999, Robber);
OR
Clerk.Tasks.PutHandsUp(int.MaxValue, Robber);
Things to check after trying that code...
1. Make sure that you are not calling the task constantly (eg: in a tick type method), ped tasks when reset too quickly will result in the action being canceled.
2. Make sure that neither the clerk or the robber are null at the time it's called.
Matt