finale 2014.5 multi measure rest problem in part. 

I have a trombone and piano score, and when I edit the trombone part is not letting me create multi measure rests. I actually click the create option and nothing happens.

Somebody knows of an option that doesn´t imply copying in a new document? Because that works if I copy little by little and make sure to not copy where I have measure rests. But leave the measures blank to create the multi measure rests after. ...