WD4A: pass user id from view application parameter to wedynpro iview

I have created one webdynpro application and deploy the same to sap enterprise portal, application working ok but I am not able to capture user id which, I have passed from Portal IView application parameter to webdynpro.

Steps done by me.

1. Declared User ID parameter as STRING in HANDELDEFAULT of main window, WebDynpro Application and component controller.

2. Created one iview on portal side and pass application parameter as USER = <User.LogonUid>

Application runs fine but USER parameter comes blank from portal. please tell me how to resolve this...