Can you use a tamron Lens with a nikon d40x?

I got a Tamron SP AF90mm F/2.8 Macro 1:1 for christmas i can't figure out how to get it to work with my camera. All it does is focus in and out constantly then it will take 1 picture out of 10. I need to go back to the store it was bought at for a lesson but its over 3 hours to get there and i won't have time in the very near future i just want to make sure it's compatible with my camera and maybe what i'm doing wrong?

Added (1). I was trying to take a picture of a bow on a present. With my tripod.

Added (2). Ok thanks now i will try it in manual and maybe that will help and i will make sure i have enough light as well.

What are you trying to take a picture of?
Yes the lens is compatible

It is compatible with your camera, otherwise it wouldn't work at all. The focusing issue is worrisome though. Either you're trying to get it to focus on something that does not offer enough contrast or in too little light, or this particular lens may have a focusing defect.

That lens is compatible if you got it in nikon mount which you seem to have done.

It's a bit finnicky to focus this lens, it needs quite a bit of light and even then it's not the fastest. That's one of the reasons why you can switch you manual focus by pulling on the focus ring.

You haven't got enough light and the auto-focus is hunting. Simple as that. When shooting macro on a tripod you will being focusing manually anyway.

More light is the answer.