I was about to post a negative comment about my WIFI unit. Luckily I didn't.
I have a couple of X10 modules in my den. An appliance module and a light module. The WIFI unit did not work with either, but my old Maxi Controller did.
I ran an extension cord to another outlet. No dice. I then ran the cord to a power strip that had a new Dyson fan/heater combo plugged into it. I unplugged the Dyson to use that socket and the WIFI controller worked. Thinking there's something amiss with the other outlets, I plugged the Dyson back in. No more WIFI control.
The Dyson is going back tomorrow. The other outlets now work.
A lucky break.