One Key on M-Audio Keystudio not working in Logic Pro 9

For some reason, the D#4 key on my M-Audio Keystudio MIDI keyboard doesn't work regularly within Logic Pro 9. At first, I thought it was a hardware problem with that one key, but I tested it by changing the octave higher & lower & it works then. I also tested it in MainStage & Ableton & it works fine there as D#4. I can get a sound out of it sometimes, if I move the modulation wheel, but that doesn't always work either.

Can someone help me out with this?

Thanks.