PA40 position conflict - error message setting

Dear Gurus,

Please help me to convert the below normal message to severe "error message" .

This assignment conflicts with personnel number 00123456

Message no. 5A229

Diagnosis

You are trying to create an organizational assignment for this person that already exists. The person specified in this message is already assigned to this organizational unit.

Your system is set so that multiple assignments are not allowed.

Check that you entered the correct organizational assignment.

If necessary, the person currently assigned must first be transferred before you can assign the organizational unit.

regards,

Bala