Edit - I meant level 5, not level 4 I guess you can;t edit the name of a post.

I managed to get past the pit puzzles on this level and the only thing I have left to do right now is get through the timed puzzle where you have to throw a rock at a plate and get through a grate to enter a wooden door.

As with all of the other timed puzzles, I've mapped out my moves, and that's worked beautifully for me so far. However, on this puzzle I always end up getting stuck because the grate is going up just as the wooden door is coming down. In other words, I am "bumping my head"on the rising grate as I try to go through it, and helplessly watch the wooden door come down before I can get past the grate.

What on earth am I doing wrong?

Edit. As usual, the second after I post I got through the gate.