Reaper Won't Begin Recording

Hey all, Sorry for this noobish question but I'm kind of stuck... Reaper is not letting me record on a track. When I hit record the cursor (the line that runs vertically across all the tracks) just sits there and flashes instead of moving across the screen which is what it should do when recording properly. I've got the track armed so I'm not sure what could be causing this problem. I'm using a Tascam US-1641 usb interface. This problem just arose and as far as I'm aware I haven't changed any other settings. I'm a little puzzled... Anyone have any advice? Thanks

Sounds to me like a audio interface issue. I would go into your audio device settings and click on the asio configuration button and see if everything looks ok.

You were right. Turns out I just needed to update the firmware. Thanks a lot for the help! It would have taken me all night to figure that out...