interesting issue..... need gas furnace troubleshooting help

Greetings all! Woke up this morning to find out that my heating system is not turning on. Sentry s-90 dp gas hot water system, 1 zone. I spent the last few hours reading and researching, putting pieces together but there is still something missing. The problem: When the thermostat calls for heat, the relay clicks but the damper does not move, therefore heat does not go ON. But....