Vista - Messenger on Windows Mobile 6 doesn't recognise MS Office Communic

Hi,

Bit of a strange one this.

Background - I have several friends/colleages who use MS Office
Communicator, and I have them set up as contacts on my WLM. This works fine
on WLM when I run it on XP - I simply add them as a contact and we can see
each other's online status and chat no problem.

However, when I run WLM on my Smartphone which runs Windows Mobile 6, it
doesn't show these contacts as being valid Messenger contacts. I can't see
their online status, and I can't initiate a chat with them. BUT, they *can*
see me online and they can initiate a chat with me, and we can then chat
normally..... i.e. if they start the chat, it works perfectly, but I can't
start a chat with them because WLM shows them as "non-IM" contacts.

So...... it seems that WLM on Mobile can talk to MS OC contacts, it just
doesn't show them correctly so you can't initiate a chat with them..... Is
this to be expected, or is there a fix for WLM on Windows Mobile 6? I can't
find any info regarding updates to WLM on Windows Mobile at all - the
official pages just say that WLM comes with Windows Mobile and that's it......

Any help appreciated!