hi everyone. I've just fitted a new back brake pipe on my 2012 gasgas txt pro. I've been bleeding the brake. you know. the usual undo, push, tighten, release method. after an hour or two of doin this the fluid stopped going down in the reservoir and no bubbles were coming out, and when i released the nipple, and pushed down on the Lever, fluid started to come out of the nipple and still no back brake is working. this is my first time bleeding brakes. any suggestions?