You have changed the panel correctly in the panel.cfg, so that is not the reason you have no ammo (0000).
However. If there is a syntax error in the CSWeapon.xml file, that will give you no ammo (0000).
So I would say something is wrong with the CSWeapon.xml file. It could be missing altogether if you did it manually. You may have forgotten to copy it from some other aircraft that has Weapon added to it and pasted it into the aircraft you are working with.

I often remove the HUD Glass from the panel.cfg but not the HUD itself. It works fine like that.