Serial Number is already Locked by User

Hi,

We have ISU Material where Serialization Profile is activated system. We create Serial Number Automatically when we do the MIGO. The System is giving me a error that " Serial Number is already locked by User".

If I enter quantity say for Example 9000 in the quantity field, system is allowing 7000 and 2000 it is throwing me the above error.

I have also unchecked Lock for Internal Assignment of Serial Numbers in SPRO settings of Plant Maintenance Module, which results in increase the acceptance number from 3000 to 7000. But beyond that it is an issue.

Please help me

Thanks

Subc