A problem with SCIM: runs, but doesn't work

[jan talentex demon co uk]

This one may seem a bit off-topic, but I hope you will bear with me. The reason I ask here rather than on the 
gtk-list gnome org is that I think people on this are more likely to be able to pinpoint what is going wrong; 
please let me know if I'm wrong.

I have installed the latest version of SCIM, following all the instructions I could find, eg. here: 
http://www.scim-im.org/wiki/documentation/, and it runs, if I run it in a terminal:

# scim
Smart Common Input Method 1.4.2

Launching a SCIM daemon with Socket FrontEnd...
Loading simple Config module ...
Creating backend ...
Loading socket FrontEnd module ...
Starting SCIM as daemon ...
Launching a SCIM process with x11...
Loading socket Config module ...
Creating backend ...
Loading x11 FrontEnd module ...
GTK Panel of SCIM 1.4.2

Starting SCIM ...

But that's all - I can't call it up with Ctl-Space or anything, although I have configured it that way; in 
fact it seems to be in a world of its own. I think I have all the locales I need (most notably simplified 
Chinese):

C
POSIX
de_DE
de_DE euro
en_HK
en_PH
en_US
en_US.utf8
es_MX
fa_IR
fr_FR
fr_FR euro
it_IT
ja_JP
ja_JP.eucjp
ja_JP.utf8
zh_CN.utf8

What makes it so frustrating is that I have had it working (even OpenOffice), but I decided to upgrade my 
desktop (GNOME); and now I just can't get it to work at all. Are there any logfiles anywhere?

I can see it listening in netstat etc, so I would have thought it would work - it is as if GNOME or whatever 
simply doesn't look for it, so perhaps I need to look at what happens from that end. Are there any 
configurations I need to set up for input methods to work?