SAP Message WS540 - Tax code determination from price determn without net value not possible

Diagnosis
You have attempted to determine the tax code from price determinationalthough no net value exists for the item.
Subsequent determination of the net value is not normally possible ifsurcharges or markdowns or other conditions affect the gross value.

System Response
INCLUDE ISR_STOP

Procedure
Enter the net value of the item. In some cases you can change the grossvalue manually after entering the net value.