I'm not able to find a specific value using debugger on Ikari warriors.

At maincpu@FDEB there is the ammo value for P1, that when game starts is set to 99.

If I try to find the above value using:
cheatnext eq,99
show 0 cheats.

by typing "cheatlist" it seems like address FDEB is out of range of possible addresses search, so this is why debugger never find that value.

Is there any explanation to this ?