Light timer - Help - No ground??

Okay so the timer I bought at home depot does not have a ground prong/slot (only the 2 slits), and when I tried plugging the cord from my HPS into a 3-prong grounding adapter (this thing http://www.radioshack.com/product/index.jsp?productId=2104010 ) and then into the timer it didn't work. So does anyone know if this can work somehow or does the HPS need to go through a grounded timer?

I'm on day 20 of my grow so thought I should switch from 24/0 to 18/6 for the last week or two of veg..

Thanks guys.

dud ehtey sell those at the dollar store go buy one or 7

they sell what at the dollar store? I already have the 2-3 prong converter I am just wondering if I have to go buy a new timer or not.

Thanks for any help

nvm thread can be closed I fixed it.