How to copy Key Figures across planning levels

Hi,

We are working on an implementation of supply planning in SAP IBP4.0.

I need to copy Key figure DependentDemandAtPlant@ProductShipFromLocation to DependentDemand@ProductLocation

Here ShipFromLocation is a reference master data type that refers to Location master data. Even though both are the same master data I get the error that 'There is a mismatch in the input and output planning levels'.

Kindly suggest a workaround and also please elaborate on the use of reference master data type.