heat pump not switching to heat

Hi all, One of my electric baseboards stopped working and I'm not sure what troubleshooting step to try next. I'm a bit stumped. The whole house is heated via electric baseboards. Last Winter/Spring, a professional renovation was done where two walls were removed to create a common area kitchen, dinning, living room. Where there used to be two thermostats for two 8' baseboards, there is now just one thermostat for two identical, new 8' baseboards ([URL="http://www.ouellet.com/en-ca/products/residential-products.aspx?product=OFM"]Ouellet[/URL] brand). The master electrician said there is no single thermostat that could handle the power of these two baseboards, so he installed a 110V thermostat that drives a pair of RIBU2C devices/relays ([URL="http://www.functionaldevices.com/building-automation/display.php?model=RIBU2C"]link[/URL]). This worked nicely and quietly through Spring, maybe 6 weeks. The heat wasn't used during the Summer, and now this Fall one of the two baseboards is no longer heating up. I'm sure no electrical work has taken place since, and I don't recall the impaired baseboard being banged. It certainly sports no mark indicating damage. So I did a little troubleshooting. When the thermostat calls for heat, there is indeed 220V at the cold baseboard. After shutting off the breaker and disconnecting the baseboard, I measured the heating element resistance and it registered 30 Ohms, which is exactly the same that I got from the working baseboard, and which seems to make sense for a 4000W board (11.5A squared times 30 Ohms = 4000W). I think there is a high temp limit switch in them baseboards. Looks like a black plastic think hooked up to a bare copper wire that runs a couple of inches above the heating element. That switch measured zero Ohm (ie closed) which I would expect. From the above, I deduce that the baseboard that won't heat appears otherwise healthy. In my attic there is a large junction box containing the pair of RIBU2C's. When there is a call for heat, one LED per RIBU2C lights up, but it doesn't stay on steady. I didn't measure exactly, but it's like 12 seconds on, 5 seconds off, repeat. I have no idea if that is expected, but I'll guess yes since it works for one of the baseboards. So, if the thermostat is working, the cold baseboard is showing no fault, and the relays are behaving the same way, what the deuce could it be? How was my baseboard troubleshooting procedure wrong? What am I assuming about the relay that may not be true. Thanks in advance, JP