Ceiling Fan Generic problem (unknown brand)

I recently bought the compact florescent light bulbs from Home Depot and tried replacing the burned out bulbs in my ceiling fan. There are 3 bulbs per fan and 2/3 work fine, but the third never works. I've tried moving the position of the bulb with one I just saw working and it doesn't work in that one socket. It's not the socket because when I replace that one bulb with an original incandescent bulb, all of them work fine. I made sure when buying the CFL bulbs that they were the exact replacement equivalent (60w-60w=13wCFL) with the correct base (intermediate [newest base type, very rare]). Any ideas why this happens? Is it because they are running in parallel or series and they're not getting the power they need?