Why does this plane not pitch up after a dive? I've tested my RC plane yesterday. It's a canard. After hand launching, the plane goes straight, then I change the elevator to go down and it's going down, but when I pitch up the canard doesn't work and the plane crashes.


The plane is at full throttle.
When diving the plane slightly rotates to right.
Controls tested before flight.


Edit:


Airfoil is a NACA 2412, but tips gets a little thick (all cutting, sanding is done by hand)
No incidences.
One servo for the canard and one servo for the ailerons. 
No thrust angle.


The plane:


CG is just in front of the vertical stabilizer (the little cross in the image)
My vote is that the surfaces aren't rigid enough and get twisted so much that the control surfaces can't overcome the effect. How floppy (non-rigid) are the wings and the canard surfaces? The wing looks to be sagging under its own weight! My thought too is that you're tail heavy, tail heavy will pitch both ways and you can get stuck in either positive or negative stall (or tuck). Tail heaviness causes the plane to tend towards going or falling flat like a leaf; it's usually strongest (leeast recoverable) when under the influence of negative G's. It doesn't matter whether the craft is upright or inverted; it's still "negative G's" including the caused airflows. Still, my best guess is weak surface rigidity. Good luck with your cool project!!!