Wrong colors using contourf()

Hi again,

up to now I've been using contourf() with the gray colormap so I hardly
noticed this problem until now: the highest values of the contour do not get
the right color.

You can see it on the 2 sample contour plots here:


I've used the standard jet colormap. Note how the highest values are displayed
in white, whereas they should have been displayed in red...

This is quite a critical problem for me, I'm ready to do anything if it can
help solve it...