Hello, I just bought a 1t external hard drive work great. I plugged it in and time machine asked me if I wanted to use as a back up and I clicked ask me later. Well now that Im wanting to set it up I cant seem to get it to work. I go into system pref, click on time machine and it only recognizes my boot camp. Please help me out, Thanks!! Also it does recognize it any where else ex. finder and pops up on desktop.