Hi Gaurang,
Quite strange..
what have you done to make this particular user to fall into exceptional case. 
If its working for all other users there can't be any issue with the configuration or parameter settings.
I would've tried to copy this user account with a new one to test the functionality if thr functionality is working.
One more point: Are you just trying to ask this user to go with the training and certification for which he/she has already gone through.?
Could you try the workflow for this user to take for a new training..see if it works out.
Regards,
Ameet