Bommom,

Based on your post, First thing to look for is:

Make sure the drain stand pipe and hose is 36 to 38 inches high from the floor.

Make sure the drain hose is not taped or sealed to the standpipe, and that the end is not stuffed too far down, inside the pipe.

What you're describing is called a "syphon" problem, and all these checks should solve your problem.

If you need more assistance, please supply a proper model number.

Thanks,
:) :) :)