Mine did the same thing (ARO Ballast and URI Actinic) I would get them to fire and then they would go out. I would get the flickering and then nothing again. I turned off the ballast and walked away and when I returned I check all the connections and end caps turned on the ballast and they have been working fine since.
When you say flicker is it an attempt to fire and then it goes out? Do you hear a little "sizzle" sound?
