Here are the steps that most often resolve the issue: 
1. Make sure the audio cable is fully plugged into the iPad and the iPad volume at the maximum. 
2. Make sure the latest version of iOS and EventBoard is installed. 
3. Check that the color frequencies are properly set in the TEEM EventBoard dashboard. If you're not sure what this looks like, you can see a screenshot of the TEEM menu here:
https://support.magtarget.com/slides/slide/teem-eventboard-color-frequency-setting-31
        Green (available): 1500 Hz
        White (check-in): 670 Hz
        Red (occupied): 370 Hz
4. Restart the iPad
5. From the iPad play this test video:
https://magtarget.com/test
If the light color match the color of the screen then the enclosure is fine and your problem is on the TEEM/EventBoard side.

If the issue persists after you've tried these things, please let me know!