LM 1200 Failover on Business Network - Problem

Our business LAN is on a fiber ISP. I purchased and configured an LM1200 cellular modem as a failover as backup. I tested it on my desktop PC, just to make sure that failover kicked in when I unplug it from the Business LAN. It rolled over fine (and back, when I plugged our business LAN back in). Great. I figured the next step would be easy. 

The next night I stayed after hours and plugged our business LAN  and the ISP Modem into the LM1200. Nope. No internet anywhere in the building. Anyone have any ideas?