First i would like to know if you have fitted back the thin plastic retainer that holds the headliner in place AROUND the sunroof opening in your roof?
The centre panel should be glued to a thin metal bracket that fits all around the inside sliding! panel and then held in place by 4 small cross headed screws.
PART of the sliding panel slides on that plastic retainer....before i go into more depth check this first!
ON the road in his SEMI!! lol