Web Dynpro iView fail to execute on portal side

Hi Gurus

I have Created Web Dynpro Application in Backend ( ECC ).

If i tested them from SICF transaction or SE80 transaction they are working fine.

Now on Portal side, I hav created Web Dynpro iView for Those ICF Services (Web Dynpro Apllications).

But most of time they Fails to execute from Portal side.

Symptoms :

On Browser Status Bar It keep on refreshing that iView address.

and Nothing comes on O/P side.

What culde be the Problem ?

How To resolve !!

Thanks & Regards

PK