SAP Message C6020 - Quantity conversion not possible for price determination

Diagnosis
The system tries to calculate a price for the material to be produced.To do this the production unit must beconverted to the base unit of measure.
However, the conversion cannot be carried out.

Procedure
Check the production unit and the base unit of measure in the materialmaster for the material to be produced. Check in Customizing whether aconversion factor has been maintained for these units.