Dear Sachin,
Check Production version-Automatic/manual options in OPL8, also, check theTasklist tpe selection in OPL8. But the highest Priority is the Selection ID which you have maintained in OPL8.
If You not maintained the TaskList type in this Selection ID, system will throw an error and you cannot able to create an order.
PROD.VER is mandatory for Prodcution Order creation. Anupamji, please correct if I am wrong.
Plz check & Revert.