Hi Vadamalai,
Error screen suggests your rule resolution was unable to find any agent,
Check in PFAC (rule simulation) after passing relevant values as per binding whether it is really unable to find the AGENT.
You can check by putting a break point in function module and identify where in your business logic it is failing.
Above approach will be helpful if your task/rule is custom, if it is standard then look for the business logic in relevant documentation
-----BR----
Tapomay