Why do I lose weights when I import rig to unity?

I am trying to export my rigged character to fbx and import it in unity. All I have is a mesh that is smooth-binded to a skeleton. when I export to fbx and import it in unity I lose all weights on the mesh and the bones don't affect the skin any more. In the fbx exporting settings I have checked Animation and Skin and it still doesn't work. Since then I've been trying every combination possible and still I get no result.

There is someone who also had problems with exporting skin weights to fbx and tried his solution which was to reset my maya settings but still my exporter loses the weights.

I only need the skin to be affected by the bones so I can use a script to move my bones around.

What am I doing wrong?