error in FBB1 postings through F.05

hi

i am using F.05 tcode to post fbb1 documents

do f.05 tcode creates any BDC session if so where it is done

and the error is RF05A-NEWKO is getting populated with a wrong value

i need to know from where this screen field is getting filled and how and where the BDC session is created and how to resolve this issue

points are for sure