Hi Kiran,
1. Are you facing this problem for all the users or for some specific users.
2. Users exists - then go to PPOMA_BBP --> User level -->who created the cart -->Double clcik the user --> Check "CHECK TAB: for any errors
3. Are there any errors there? If so it should tell you how to fix them using BBP_CHECK_USERS.
Thanks.
From RBEI,
Snehal