Radio Button / Tab Group Index Value / Window Index Value

Hello,

I'm a newbie to applescript. Using Quicktime Player 7 I'm trying to automate "Save As" and select the radio button "Save as a reference movie"

The line below in red is hanging me up. I can't figure out the index value for tab group and window. For all I know the entire line could be incorrect. The error returned reads error "System Events got an error: Can’t get window 1. Invalid index." number -1719 from window 1"

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activate application "QuickTime Player 7"

tell application "System Events"

tell process "Quicktime Player 7"

keystroke "S" usingcommand down--SAVE AS

key code 124 --RIGHT ARROW

keystroke "_STEREO"

tell application "System Events"

click checkbox "Save as a reference movie" of tab group 1 of window 1

end tell

end tell

end tell

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I then run a separate script to try to get a read out of the windows info be but it doesn't return data that's helpful. I assume that it is index value is "1" since the Save As window drops down and is on top of the only other open window in quicktime.

tell application "System Events" to tell application process "QuickTime Player 7"

properties of window 1

end tell

Any thoughts?