Hello, I've edited my original post to be more concise. Updated problem description below. In an effort to trouble shoot a new Omni Notifier (that I cannot get to work--see other post), I tried switching my serial ports. Originally UPB was Serial #3 and non working Notifier was Serial #2. Then I physically changed them on my OPII board and changed their location assignment in PCA software. Since switching Serial locations didn't fix my Notifer issue, I changed both Serial ports back physically and in the PCA Serial set up to make Serial #2 Notifier and Serial #3 UPB. I "wrote" the Serial assignment change to controller and am now having problems with my Units. Here's what's happening: 1) I turn on a HAI UPB physical light switch and the PCA software recognizes the status change. (From off to on and vice versa) 2) I try to change the Unit/Light status via PCA (or HAIKU or Space) and I see the HAI UPB Powerline Interface Module light change from green to red then back to green. Seems to be working properly as the PCA software shows the Unit/light status change, BUT the actual lights don't turn on or off. I'm currently running PCA v3.17, OPII FW v4.0B, and Notifier v2.0. Any help is greatly appreciated. Thanks in advance for just reading my post. Cheers, Geoff