Thanks for the quick reply Gene. Based on the code you pointed me to, I changed my program to use the command "Thermostat.SetPointSet". I no longer get an error logged, but it's still not changing the setting on my thermostat. And as I mentioned before, the thermostat widget is also not talking to my thermostat. This was working prior to the installation of 421, so it's not a problem with Z-Wave pairing or anything like that.