Unable to convert mod_assignment to mod_assign

Dear All,

I would appreciate it if you help me in the following issue.

I have two moodle sites one has 1.9.9+ version and the other is a new moodle site with the latest moodle version 2.7.

After the installation of the new one I took backups from the old files and restored it at the new version and it was successful. But when I tried to use the Assignment Upgrade Helper to upgrade the old assignments to the new one I faced the following error:

Could not convert assignment. Exception was: Table "assignment_upgrade" does not exist

Regards,

Ali,