I have a text file with the idnumber of the students I want on each new line

When I runt he import and have assigned to group select I get errors like the below. In every case most of the students are imported but not all.

Line 2: Unable to create role assignment for userid '07046381'
Coding error detected, it must be fixed by a programmer: User ID does not exist or is deleted!Line 3: Unable to create role assignment for userid '11094594'
Coding error detected, it must be fixed by a programmer: User ID does not exist or is deleted!