Hi Neha,
First of all, is your B2B add-on properly installed? And do you have a patchlevel available which is high enough to prevent known problems? Please do read this: How to install the new B2B add-on
Next, is your runtime content properly uploaded and do you use that content within your ESR (via a generated XSD)?
Kind regards,
Dimitri
PS: there is a dedicated community for B2B integration: http://scn.sap.com/community/b2b-integration/
