It shows a fault (or flt) until the propane lights up, then it goes out. If the propane fails to ignite after a few cycles (this is the clicking you should be hearing as the direct spark ignitor/DSI is making sparks to light the propane) then the system goes into a lockout mode...... and the light will stay on but the dsi quits trying to make sparks.
To reset the lockout turn the dsi switch off, then on again after a few seconds...to start the process all over again. If you have air in the lines you may have to do this a few times. Try turning on your stove burners to purge the air and make sure you have propane delivery.
Once the propane ignites, then the fault light will go off.
If it doesn't light after a few attempts.......you may have a problem somewhere in the propane delivery...which I am assuming you have the cylinders open.
This thread may also help if you have perhaps a Suburban water heater:
Suburban's electric switch and much more