Why Blender export only exports one object out of a grouped object? I have an object which is a group of 6 cubes.

I grouped them using ctrl+G and I see a green outline around the whole object when selecting it. However, when clicking on a single part, it only selects that part, instead of the whole thing, but they seem to be grouped anyway.

When exporting, I hit 'Z', then 'B', select the whole thing, and then use the export button. It seems only the last selected object gets exported and the rest of cubes shaping the pistol are simply ignored.

Worth noting:


All these objects have a parent object which I used to move around the object once animated (so that it wouldn't impact the over all animation after moving its location somewhere else).
I'm using an add-on to be able to export .mdl files for Quake and this is the export settings I'm choosing.




What is exactly wrong? Is this an issue with the add-on not being able to export multiple objects as a single object? Is there any workaround I could use? 

Thanks a lot.

EDIT: this is the extension I'm using - https://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/Import-Export/Quake_mdl
Using Blender v2.78c.
It turned out that this add-on requires objects to be joined, not just grouped. Ctrl+J did the trick.