Better take a look -- you may have gotten it on a pulley slightly off to one side -- you know, one rib too far one way or the other.
If the belt and routing is fine, you probably have a pulley going bad that was causing the other belt to have problems. Could be the tensioner or the idler.
I've had nothing but good experiences with these belts. I think, unless you got a "bad" one somehow, that you have another problem. Make sure all your pulleys are turning and look for signs/sounds from them to try to determine what's making the sound. A paper towel roll or something that narrows down your sound pickup is good for trying to locate it -- or a piece of pipe.
Just be careful of those moving belts!!!