Santosh,
Try using different formats for the Sharepoint username.. I know it is a bit picky.
user@domain
domain/user
One of them will work.. you will need to also make sure that the user does have access to all of the sites.
Have you also followed the installation process for the Sharepoint Plugin required to even scan SP?
Make sure to follow those directions to the letter.
Thanks
Ronak
PLEASE MARKED SOLVED WHERE POSSIBLE