Why is my grading table not accepted by the GP Manager?

Error description

It is with one Grading table not possible these to utilise. With other Grading tables steps the problem not on.

Cause of error

Very probably contains the File name the Grading table invalid Sign. To the Example Space at the false Digit or special character.

Troubleshooting

Create a new size table. Name the size table only with Letters, Figures and _. The grading table should then be accepted by the GP Manager.