Blender 0 weight bones

Example of the problem: I have 5 objects and 1 armature. Every mesh is skinned to 1 bone and got 1 vertex group, but when I open this “.FBX” in unity and hit ‘show all bones’, it tells me that every mesh is skinned to every bone what could be the reason for this? I know the problem is in Blender. Opened the “.FBX” in Maya as well and its the same. Tried all kind of exports and cleans and still nothing.