You are using the standalone editor with an older MX-900? If so the newer 900 is set up for the newer complete control software and won't work on the older editor until the boot software is re-loded from the stand alone editor.

1. Remove one battery from your remote control.
2. Press and hold the “POWER ON” button and “MUTE” button same time. Continue holding.
3. Insert a battery so remote control can power up.
4. Release the buttons. LCD screen says “LOADER” (MX-900)
5. Open the MX-900 CCP or standalone editor. Download a file to the remote. Now the remote can be used normally.

Hope this helps.