SAP Message 29763 - No BOM exists for this functional location/usage

Diagnosis
You want to allocate the BOM for this functional location to anadditional plant.
However, there is no bill of material for the functional location withthe usage you entered.

Procedure
Please check your entries in these two fields.
If both your entries are correct, you need to create the functionallocation BOM, and then allocate the BOM to another plant.