first of all, are you 100% sure you are on their allow list?
does this happen to you only on your computer?
if so, it might be a problem with your msn. try uninstalling msn and installing it back again from here:
http://messenger.msn.com/download
also, (in case this happens only on your computer)
it's a long shot since usually the problem is that (the person's contacts who are online doesn't appear on the screen screen on their list) but do you maybe have the handwiritng plugin installed?
if so go to the drive where plus was installed for instance (c:\program files\messenger plus!3\plugins)
delete the file MsnHandWriting.dll from your Messenger Plus! Plugins directory.
than go to add/remove programs look for the "ink redistributable" or "InfoPen", if you have either than click it and uninstall it.
if what i said above did not work or does not apply to you
maybe your contact list is corrupted. (i'm not sure hot trillan works at all
... if it uses listcache.dat)
/ 
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