Hello,
I think your user is not vendor. You could try under order & shoppers -> Shoppers, select your vendor user user and click on the top left the button "is a vendor".
If this did not work then open your database using phpmyadmin and go to the table xxx_virtuemart_vmusers, find your user id and be sure that haves "1" in both virtuemart_vendor_id AND user_is_vendor. The other users should not have user_is_vendor=1, so if haves place it to "0".
Regards