some key binding combinations execute singly, but not when combined

The following key bindings:

"n" = ("selectNextCountedMailbox:"); "m" = ( "makeFirstResponder:", "mainOutline", "nextUnreadMessage:" );

execute as expected when pressed in sequence.

However, the combined key combination does not execute properly:

"n" = ("selectNextCountedMailbox:", "makeFirstResponder:", "mainOutline", "nextUnreadMessage:" );

From playing around, it seems to me that that the last three commands are attempted before the first command completes.