Diagnosis
You are trying to change the usage type from $v1$ to $v2$. Howeverdifferent reference areas exist for these usage types in Customizing.

System Response
The system allows you to change the usage type, but you should be awareof the following: if an existing rental agreement is processed with anold usage type after the usage type has been changed, the new referencearea will be used and the data of the rental agreement will changeautomatically.

Procedure
Decide whether you really want to change the usage type. If so, avoidcalling up existing rental agreements of this rental unit in the changemode.