How do you know "your tanks" have spotted the enemies "you know are there".You have the "Godspot". all knowing information of the battlefield, your tanks do not.You as a new player may think they should be spotted, but the game engine is saying "no spot" for some reason that we cant tell(smoke,dust,haze,trees,etc.) with out a nice video or some screen shots.Also sometimes due to the elevation mechanics of the game the commander sitting higher up then the crew will spot, but due to "the crew/gunner"being lower in the tank, the tank will not shoot, because the gunner needs to spot.