Rear slide wont move??

Hi guys. So I have a confusing problem. We recently got back from a trouble free trip in out 2005 Newmar Kountry Star. Upon arriving home I put all 4 slides out to unload. I left the slides out for a few days and during that time I replaced both of the coach batteries. I then went to put the slides in and all would go in except the rear curb side. Nothing at all would happen when I pushed to switch. I found a blown fuse and replaced it. Now the green light comes on when I push it but nothing else. So I went out side and hooked up a direct 12v source to the slide motor and the slide went in. I can reverse the 12v source and the slide will come out. It sounds a bit different then it usually does when its under its own power, but it works none the less. I thought it might be the switch but it will run the other slides when I change it out so I know its good. I have checked every fuse, breaker, etc. I have tried while on battery and shore power. Does anyone have any idea what the problem could be? Or at least give me something else to check?? Any advice is greatly appreciated....I am at a loss.