Serial number prefix in MM

[azappi]

Hi Members 

I have the challenge that I need to add a prefix to my serial numbers, when I create a new purchase order, so far I have created a new category and a number range.  

I also created a serial number profile in MM and maintained my prefix, the issue is, that when I create a new PO in ME21N, the correct number range are picked but without prefix, it is important that the supplier got the information about the prefix, so how to show the serial number incl. prefix in ME21N and the output form?

Any ideas?