Magnification ability does not work!

[sandrah9 at comcast.net]

This is a request for help with the magnification tool.  I am using Rev. 2.7 on Mac OSX 10.4  and am trying to magnify an image so that I can make some corrections.  Previously, in Rev. 2.6 all I had to do was click on the control key while using the pencil tool and the magnification palette screen would appear.  According to the new Rev. 2.7 documentation, I should be able to do the same thing.  

However, all I get are two new screens -- the magnification panel which is empty and another bizarre black screen with pixels in various colors (not from my image) that appears to be floating in cyberspace.  It is almost as if the magnifcation pallete has developed a schizophrenic personality . . . leading to no utility whatsoever!!

Is there anything to be done?

Hoping for advice,
Sandy