SAP Message UPP_PP_K028 - There is no valid previous combination

Diagnosis
You have reached the first valid combination of characteristic values.You can only scroll within the characteristic value combinations, whichresult from the current selection criteria in the planning area orplanning level. For this reason you cannot scroll any further.

Procedure
In order to display or enter values for other combinations of othercombinations of characteristic values, change the selection criteria inthe context of the planning package or planning level.