Tele converter option for Tamron 28-75mm f2.8

Tamron makes their lenses with a variety of lens mounts. If your lens has a Nikon mount then it will mount onto the D90.

As you can read in the Dpreview link the Tamron converter can work perfectly with the Canon cameras. Question is, will AF still work, because you have to multiply the aperture twice. So if your lens has f/1:5,6 that will become f/1:8. Most camera's can't auto focus anymore on F 8

link to Dpreview Tamron 2X converter

The Soligor C / D 7 is a tele convertor. If you want to use it on a Nikon, I hope you have the correct connection. Your question implies you are planning to using this with a mirror lens. Most miss or lenses, come with f/1:8 and the convertor will make that to f/1:11. Most cameras only can auto focus till f/1:5,6, so when using this, forget auto focus, because that won't work.

You can order the Tamron 2x teleconverter here. Be aware that not all lenses are compatible with teleconverters, and you can actually damage some lenses by trying to use them with a teleconverter.

This lens is compatible with your Nikon D90 according to this site:

http://lenshero.com/lens/Tamron-14mm-f2.8-IF-Nikon-f-lens

Your complaint "does not work" is rather broad, so I don't know what specific kind of problem(s) your having with it.

If you continue to have issues with it, make sure other lenses work on your D90 to eliminate the body as the source of the problem. Consider performing a 2 button reset on the D90 (and resetting any other customized settings to defaults) and try again. If it still "doesn't work" then contact Tamron to evaluate the lens for possible repair.

Good luck!

Attaching the lens will make no difference.
It sounds like the release button on the camera may be faulty.

Tele convertors on their own do not focus - that is achieved by the lens. Are the lens contacts clean and correctly aligned with those in the camera ?

When using a TC, as the perceived focal length increases and the aperture falls off, AF struggles to work except in very bright light.

The rear element of the lens is near the mount the converter
will not fit the conveter needs about 10mm space at the
back of the lens

AS you have found out, the Maxxum AF mount and the MD mounts are much different. They do make tele-converters that allow the use of MD (non-AF) lenses on a Maxxum series camera. You would still need another adapter to make the MD Tamron converter work,