I have read in a couple of different posts about brakes not setting imediately when you use the manual slide, one person even said their brakes did not set until rolling about eight inches. I am curio...
The important thing is to watch the trailer and see if it moves the same few inches, when the TV moves the first few inches. If both are moving, you're probably hitched. If the TV moves and the trailer doesn't, you're not hitched.