Workflow on Opportunity changed Stage not working

Trying to create a workflow to send an email every time an opportunity is changed from  Closed to something else

I can't get it to fire

AND(ISCHANGED(StageName), (OR(PRIORVALUE( StageName )= "Closed Won",PRIORVALUE(StageName )= "Closed Lost")))

It will fire just on the Stage change, but not with the Priorvalue change.  Note, i reordered them and tried Contains instead of using an OR.

Any suggestions?

ANS

So you want it to fire if the stage is changed and the prior status of the opportunity was closed, is that right? That's what your syntax says right now. Assuming that is the case you can simply down to this:

AND(
ISCHANGED(StageName),
PRIORVALUE(ISCLOSED))