Accelerator Keys in menus

I have a main form which opens a second form.  On the main form ALT-G will
open the menu item with G as its accelerator key. On the second form this
does not happen. If J is an accelerator key on the main menu of the second
form, ALT-J simply beeps but pressing and releasing the ALT key puts focus
up on the main menu and then pressing J will get the appropriate menu item.
Any idea why ALT-J does not go directly there?
Terry Brennan