Enhancement in mb1b

Hi Abap Gurus.....

I have to create an enhancement in mb1b where I have to use movement type as 309 and transfer material from f03 to r001

Now in f03 material measurement unit (base mesurement of value) is pc (Pieces) whereas in r001 (which is scrap) unit is kg (kilogram).Conversion criteria is that 1pc = 50 kg. Now the enhancement is that when I transfer the material say 2 pc (pieces) fro f03 to r001 in f03 stock , 2 pieces should be removed and in stock of r001 100kg should be added. While transferring the material storage Location and plant location are same.

While doing so we got an error "stock keeping unit pc and kg differ". Please Help me Solve this problem.

regards,

rikin.