I can't back up my ipad 2!

Ok so I've looked up this problem and done all the things that are suggested but then I realized they were instructions for backing things up on ICloud, I want to back up my IPad right to my laptop. I don't know what's wrong, every time I think its working this message pops up "ITunes could not back up "---- IPad" Because an error occurred." I want to update my IOS and need to back it up first, and I'm aware I can use ICloud to back up my device but I lost all my info last time I did that. I don't know how else to describe this problem, any help would be very apprecitaed