Will not restart. Ignition lite flashes

Question

reddy heater model# 016920475 heater fired first time after sitting for maybe a year. I cut it off after about 15 minutes. after aprox.20 minutes I tried to restart and it would not. The ignition lite blinked off and on. Following the instructions on heater it still would not restart. What can I try. Thanks for your help. E-mail add. [e-mail]