pairing roland rd-500 to garageband

I recently purchased a used roland rd-500 and wanted to use it as a midi controller with my presonus firestudio mobile to record onto garageband. The first time I used it it worked, but later on I went to use it and now I cannot get it to work. I have looked at the manual for it and it has instructions regarding setting the channels but nothing I do seems to work, is there a driver or something that I need to make it work?