IT website registration issue

Dear Friends,
I have applied for PAN, immedietly got E-PAN and later got physical card.
When i try to register in Iincome tax website for e-filing, getting following error.
Error : Name entered is not as per PAN. Please retry. 

Tried all combination including specifying expansion of initials.

Can someone please help me in solving this problem.

Name on PAN : KIRAN KUMAR K S

I have verified PAN also. It is showing "PAN is active but details is not matching"