Diagnosis
You have changed the allowed values.
The characteristic has already been used. The system check of thevalues already assigned has found at least one case where thecharacteristic has been assigned a value that is no longer within therange of allowed values.

Procedure
Undo your change.
Before you change the allowed values, first check all values assignedto the characteristic and delete or change the values that do notcorrespond to the allowed values you want to change to.
To see a list of where the characteristic has been used, chooseEnvironment -> Where-used list from the characteristics menu.