I fiddled around with IR detection at the weekend and got it nicely working with my Arduino. I forgot that the IR module I had could only detect a modulated (flashing) IR light. I thought it was an IR photodetector so I had the light on and expect to get some kind of analogue value out of it.
Eventually I started to flash it at something between 38kHz and 50kHz and it worked fine.
There is some useful information on this Arduino page.