Sahil,
I have not gone through your complete post, sorry for jumping into the discussion. But, believe you were trying to access work item for approver (Manager, I think)). I noticed that you added "ZGRAC_MANAGER11 " as approver agent id and the approver type is "Directly Mapped Users".
May I know if you have maintained any User id for this type of agent? Secondly, are you checking correctly for the maintained approver id?
Regards,
faisal