Dusty Ratcliff

well I finally got around to putting my new a/c compressor on, first I was just going to switch out the clutches since my old compressor was ok i figurred it would save a few dollars by not having to flush & recharge the whole system, this didn't work too well cause the shaft on the old compressor was smooth with a keyway & the new one was splined with a keyway, so I put the clutch back on the new compressor & switched the whole thing out, took the truck & had it charged & now the clutch stays engaged all the time??? I'm gonna pull the plug in apart today & see if it disengages that way, but if not I'm not sure what the problem is??? any ideas??