SAP Message VK321 - Condition type & is not a condition type for taxes

Diagnosis
You have tried to assign tax condition type &V1& to condition typegroup &V2&.

System Response
Assigning a tax condition type to a condition type group is not allowedand therefore rejected. Tax conditions cannot be used in agreements.

Procedure
Please select a condition type which represents a price or a discount/surcharge or a rebate.