I'll poke around it (my mod after all :P) when I get a chance.
But in the meantime you might try just using the mod extracted. If you put the extracted files where they go in the game directory you can just use it that way then you don't have to bother with paking it. Then unsubscribe/delete the .pak file of the mod.
Have you checked to make sure that you're actually looking at a "Goblins_Tank_A" and not a "Goblins_Tank_B" for example.
