Link Between Activity Types and Activity Input Planning 

Use

A direct link exists between activity type planning and activity input planning. This can have the following effects:

If the scheduled activity is not the same as the plan activity after activity input has been planned, then your planning may contain inconsistencies: The plan credit of the sender cost center that was posted by the SAP System as a preliminary credit to this cost center does not equal the total of debits on the receivers. This means that either more or less activity was used than was planned on the sender cost center. You should therefore carry out plan reconciliation after completing your planning.