Personalization

Hi Experts

Please any one help me...

I am facing the problem ,when i click personalization tab in Left of Portal . In Personalization when we click usermapping

for SYSTEM -

> SAP R/3

USER -

> XXXX

PASSWORD -

> XXXX

clicking on save button , It gives following error ( could not verify the cerdentials supplied with the R/3 reference system . Check your cerdentials, If they are correct , make sure the desired system is available ) is there any one to retify my problem

Regards

Krishna