Not detects mesh as object? that's my first question here in blender stackexchange, so I'll try to be specific;

I have modelled a city with more than 30 objects, but my problem is that Blender not detects each mesh as object. I mean, when I select each "object", in the upper menu where displays the project info (verts, faces, ) says 0/2 objects. 
I don't know why shows me 0/2 objects instead of 0/30 objects. 
I've found 2 buildings that Blender detects as objects, but the rest of the models doesn't recognise them as objects.

How can I "set" the other models as "blender objects"? 
I need for exporting them to 3ds files, and Blender won't export anything if is not an object.

thanks!




(I restored a previous file where it detects 4 objects instead 2)
I have each kind of building in separate layers, but the object's number doesn't change if I change the layer where I'm working
Select one of the object and click this button



Use the scene's active camera and layer in this view rather than local layer.

It has link in one scene into other scene



For more information please watch this video