problem with groups

[Jon]

I have a group of buttons called EditMeasurePhraseGroup.  When I try to 
alter the visibility of that group, using the following statement:

set the visible of group "EditMeasurePhraseGroup" to true

I get the following error message:

         executing at 11:57:55 AM
Type    Chunk: can't find background
Object    TapRB
Line    set the visible of group "EditMeasurePhraseGroup" to true
Hint    true

I have no idea what is going on.  The group name is spelled correctly.  
Any hints?!?

Jon