Why does the system show error ‘Invalid Free Value’ while saving despatch ?

Cause:
System will not allow to save despatch and will show message ‘VTFREEVAL2′,’ Invalid Free Value!’, ‘ Chargeable Value of group of items is not eligible for the free Value ‘ if the added item is not chargeable and still the amount is 0. When the rate is 0 for a particular chargeable item and the user tries to save the despatch with 0 value.
Suggestions:
When the user adds an item in despatch, users need to ensure that the price list and rate are properly getting populated. Users can remove and add the item again if rate is not picking up. If the item is not a scheme item then its rate should be available. After the value is populated the users can save the despatch.