Piano Roll Lock not working correctly. Sonar Platinum.

Hi,
I have two midi tracks displayed in Piano Roll.  I lock the number one track.  The button turns blue.  I can edit the remaining track.  Next, I deselect the blue track.  It turns back to white.  I select number two track button.  It turns blue.  The problem: I am unable to edit either track.  What am I missing?
thanks,
Warren