What causes erratic operation of my 6022 ritetemp thermostat? I had a room temperature of 62 F, and setting of 80 F, and the thermostat would not call for heat.

When did you last replace the batteries? They need replaced once a year and make sure its not turned off or to cool.
http://www.ritetemp-thermostats.com/60XX/images/6022_operation_guide.pdf

The batteries were new 4 months ago.

Try this next flip the switch between off cool and back to heat... maybe someone bumped it or played with it.