Hi
I hope this may able to help you, You have make changes for serial number profile that you are using.
1. Goto T-Code SPRO -->Plant Maintenance and Customer Service->Master Data in Plant Maintenance and Customer Service
2. Click on Technical Objects --> Serial Number Management
3. Define Serial number profiles, then select the serial number that you are using, then double click on the serializing procedures
4. Then for MMSL Procedure Change the Serial Usage --SerUsage indicator value from 2 to 3.
Try to verify the same creating PO then performing the MIGO
Thanks,
Jagdeep