Problem help please :(

hi , so basically i went to water my plants to day but before i did i waited for the light to come on on the timer, once the timer clicked on my cfls come on but my 600w hps didt, i figured the bulb had gone so i took it to the shop and they gave me a new one, i went back and screwed it in but the new bulb still didt come on , so i tried the cfl with the ballast and the cfl come on? i dont understand ?

is their something wrong with my ballast, like a fuse or some sort, i know its the ballest because the bulb is brand new, why does the ballast work on a cfl but not the hps :/ could it be a fuse? , please help need to get this sorted immediately :/

This makes no sense to me. A 600 watt bulb and ballast shouldn't work with a cfl. The socket should be much smaller on the cfl then the HPS. What is the wattage of your CFL? What is the make of your ballast and how old is it?

they fit perfectly, the cfl's i have are big and they fit in sockets the same , the cfl i think is 250w , the make of the ballast is illumi and i got it like 3 weeks ago :/