Airport Express disappears when backing up to Time Capsule

I just purchased a Time capsule and the new Airport Express N. I configured the AX to join the TC network so I could send my iTunes songs to it to play via Airtunes. Now whenever Time Machine begins to back up to the Time Capsule, Airtunes cuts out and the Airport Express is nowhere to be found in Airport Utility. Has anyone run into this problem? I set the Time Capsule to 5GHz N-Only.