see the technical help forum, i posted on your other thread in there

The nation of the gunner, gun and ship must be the same. Check that first.

Then, check if the level of gunner is greater or equal to level of gun.

Then, check if the gun have shells in the A slot.

With this, you must be enable to fire.

Thanks

I already follow your recommedation but still fails. I suspect it is a problem of
unmatched nationality in shipyard.

Any recommendation???

First thing to do is go to your shipyard and do the following checks:

1) Make sure the guns you have put in are in the R slot. It doesn't matter too much if
they're in the T slot but for the purpose of these checks you should make sure
they're in the R slot.

2) Make sure the gunners are of the right nationality and level to use the guns (you
can do this by clicking the force tab and ensuring they match the gun information
window).

3) Make sure you have ammo loaded for your guns and that it is in slot A and not
slot B (you can switch to slot B in game by pressing Y just in case your ammo is in
slot B).

Once you have checked those two things, head off to a battle.

Once the battle starts, ensure you press R to select the guns that you have in the R
slot (this is why you had to make sure they were in the R slots in step 1)

Adjust the guides a little so they are away from your team and have a test fire. As
you have pressed R to select the guns, pressing "space" should now fire the guns.