Maybe the level was a bit too complicated. :D Sorry for that.
The start is not included in the combination and must be deleted first, using the << shape.
Below is a possible solution.
Viewing post in cococo - connect colour combinations jam comments
Ohhh ok. Now I got it! I didn't get the shape was influencing the sequence. Might have been explained in the tuturial but I skipped some accidentally click everywhere :D. Super cool! A cool edit would be to give a special color to those shapes. Explaining they influence something else than just the sequence.