It couldn't hurt to send them the remotes - they can quickly analyze the codes themselves and see if perhaps they're outside of the range that the MX-500 can utilize. I'm wondering if the SHIFT command isn't sending a code by itself - when the MX-500 is learning, press SHIFT by itself. Does the MX-500 say "GOOD"? If so, it's a separate code that is sent to the receiver and needs to be learned to it's own button on the MX-500. Let me know how that goes!

David
www.BlueDo.com