Level 6?
Could you be more specific about which part is causing you problem?
If the problem is the beginning, then all you gotta do is be a little quick. Firstly you activate the first crystal to move some of the platforms, and the n you gotta fastly swap to the bunny character and run to the platform, jumping on it before it is too late, so you can access the upper level of the mountain.
Once there, you will find another crystal that, after you activate it, it will open the path so you can proceed.
Then you use the platforms in their new position to go back to the beginning, enter the mountain again, and now the path is open so you can continue your way! ^^