Hi Shiva,
In SPRO-->LE-->WM-->Activities--> Transfer--> Define Movement Type--> Go to Mvt type 321 and double click to see the settings.
If you have not ticked for Automatic TO creation in the above then it is created automatically for the setting done in LE-WM Interface to Inventory Management ( T-Code : OMLR). In that for the movement type 321 in column Immediate TO creation the selection might be 'A'. Only then this is created.
Also you have to process the PCN which was created as a result of MB1B (mvt type 321) by going to Tcode: LU04.
Reward if useful for you.
Thanks,
Vineeth