Pre-install script does not work

Pre-install script does not work

Trying to install MS Office 2010, using a pre-install sript to determine if it is already installed. Using script from MS which is for group policy deployment. It returns an %errorlevel% = 0 if it is installed and =1 if not. I set the pre-install script settings to continue install when a 1 is returned. This does not work, the install starts either way. I have modified the script to reverse the %errorlevel% returns as 0 is not installed and 1 is installed, and modified the settings for pre-install script to 0. No matter what I change the settings to, or modify the script, the install always runs.
 
The problem is that even though I have the scripted install of Office 2010 set to silent, it opens a dialog asing the user if they want to add/remove, repair, etc. (if office is already installed). I want the install to skip systems which already have this installed. 
 
Thanks!

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