hi ,
your portal and r3 shud be on same domains , kindly check this basis guy ...whether they are in both domains or not once ...like portal url shud be abc.com and r3 shud be also on same abc.com if it is in not same domain u get this problem once check that
945516 - Web Dynpro ABAP in a portal environment
go to SMICM and click on Go to > services in that check once with help of basis person and check in portal system object also how the domain name defined there once
