OK, I hope my miriad of questions isn't bothering anyone, but when I get the bug about learning something new, I keep trying things until something works. Since I don't have anyone at work that knows MEL scripting, I've come to you all. I'm making an install script that whenever anyone in my office needs the new tools I make, they can run the script. It works, so I'm trying to make it smart and it will only add the buttons that a person doesn't already have. This is what I've tried that doesn't work. if (!`contextInfo -ex showImagePlane`) { shelfButton -enableCommandRepeat 1 -enable 1 -width 34 -height 34 -manage 1 -visible 1 -label "showImagePlane" -image1 "showImagePlane.bmp" -style "iconOnly" -parent $selTab -command "showImagePlane;\r\n"; } Any know why it keeps installing the same buttons and how to get it to do what I want? thanks again.