Well, it finally works. You were right - I couldn't get it to work with iTunes playlists, but when I copied the songs into new playlists created (without spaces in the names) in Squeezecenter. The Indigo Applescripts now work to select the correct playlist, and begin playing.
Your help was amazing and it couldn't have been done without you. I'm a beginner in Applescript, don't know about the inner workings of servers or anything like that, so you pointed me in the right direction and I learned a lot in the process.
Again, thanks so much.
Rob