The Janome 1600p, only one way to put the needle in. The needles have one flat side so won't go in unless you have the flat side where it should be.
If you have your thread though all three holes in the pre-tension guide, try just two hole, it it still breaks, just put it through one hole.
Another thing is make sure you get the thread in the last guide before threading the needle....that was the hardest one for me to get. The manual exlains that and has a diagram, but it was still hard for me to do.