Pressure, heat and time. Try slowing things up. Looks like you started to get it darkening a little.
I did mine on parchment paper. I had hot water in a Perrier water bottle and it sitting in a rolling boil pot with the top cracked.That what mine was looking like...and it kept crumbling when I tried to roll it smoother and shinier.
I folded the paper in half and put my kief along the fold. I was doing it on the floor, so I laid a large towel down the floor.
I lightly and slowly rolled the bottle on the paper. When I saw it darkening, I flipped it over and worked the other side...lightly and slowly.
Once I got the color darker and more even on both sides, I'd open up the paper to see how sticky it was getting. Once it was evenly sticky, I snapped open the paper, much like when you press buds with the rosin. I took it and kneaded it a bit and put it back on the paper and rolled it some more. Try not to make air spaces when kneading and folding over. Keep that process going. It will take time. It will get nice, dark and sticky with time.
From what I understand, all this rolling and exposure to the heat from the bottle, decarbs the kief. Continued rolling and kneading furthers that process. My little 9g ball took me over an hour to make.
I'm gonna make some more this week.