XNA objects not occluding properly

I have got simple 1x1x1 cube model. I draw 3 of them. They are located at:

1,0,02,0,03,0,0

I draw them in the same order every time. When I move the camera and look at them from one end everything is fine. If I look at them from the opposite end I can see parts of the cubes that should be occluded by the cubes.

How can I have them draw properly?Image may be NSFW.
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