Board Thread:Questions and Answers/@comment-25523075-20161020092910/@comment-28606847-20161021060720

Just a tip: Hoppers don't use any Redstone, so if you put any next to it, it won't work.

Now, as for your question, maybe try doing what John said. Make sure to not have any Redstone connected to the hopper. I am not to experienced in Redstone, but I do know that if you connect Redstone to a hopper, it will not function. Of course, it is not possible to have an endless supply of mine carts going out of your dispenser, as it will run out sooner or later.