Multi-key and deadkey setups

[No one in particular]

Hello----

As part of the process of getting my laptop fully configured for Unicode
and multilingual support, I have been working my way through multi-key
and deadkey configurations.  For the most part, I have been able to
track down the information I need, though it´s been a long investigation
through a mess of old and new documentation.  Now, though, I am stuck
with one last problem:

I cannot figure out why some multi-key combinations in 
/usr/X11R6/lib/X11/locale/en_US.UTF-8/Compose work and some do not.  For
example, the multi-key for the AE ligature works fine, the double-prime 
quotation marks below do not, the guillemots immediately below that work 
fine.  It seems likely that somewhere there is another file controlling 
which of the key combinations in the Compose file are actually active, 
but I have not been able to determine where, or even if my hypothesis is 
correct.

I´ve no problem displaying any of the characters I have tried, and
inputting them is no problem via cut-and-paste.  It´s only getting the
key combinations to work that is defeating me.

I hate dumping a question like this on a developer´s list, but I have
run out of ideas.  I´ve been working on this project off and on for
months, and have exhausted my resources.  It may be that the only people
left who really understand how this works are the people who build it.

I´m not even sure what configuration information would be relevant
(apart from the most obvious:  XkbLayout:  en_US.utf8)  but I´ll happily
provide anything requested.

Thanks much----
ymca