Light timer doesn't always start my lights in the A/M

So, I'm having a pretty big issue. My light timer isn't reliable.
I'm running a 400w dimmable lumatek ballast on 250w setting.
it's a digital 24/7 programmable timer rated 1800w.

Is there a specific reason why it wouldn't turn on the lights EVERYTIME?

You may have it programmed wrong. I got a few digital timers and sometimes i would accidently set an extra time that would prevent lights from turning on (or off >.>)

It does "start"...I mean the timer says the light is on with the red light. However the light doesn't start. I have to put the light off and on again for it to start.
Anybody has experienced this?

Before the light starts, while it's still cold, plug it into the normal electrical socket.
Does it start right up? If not the bulb or ballast may be bad.
If it does light on the socket, I would suspect the timer is under rated or defective.