Reset CAL without effect

Hi,
I have several C10LE wyse connected to WIN 2003 server.
I often need to raz the CAL license stored in the non volatil ram.
BUT, for the second time, ClearLicense=yes or FixLicense=clean (in the wnos.ini file) have no effect.
In the startup log, I can see "Clear TS/CAL saved in NVRAM". But when I open a session, the same alert from window : your license will expire in xx days.

Could someone help me please?

thx