ballast not working properly

[rudyr03]

i had an old ballast laying around that was working last time i used it, so i thought i would supplement my halides with a 6ft 160w vho actinic.. when i set it up the ballast only lid up the far ends of the vho bulb not the middle.... so im guessing i have to buy another one.. what do u guys suggest? and if i do need a new one should i go with the icecap ballast or i can just get a regular one from home depot