Alerts: customizing links in "Optional Subseq. Activities"

Dear experts,

I have gone through blogs and forum threads but could not get an answer to my question.

Hopefully someone has an idea. I am trying to customize the links in alerting for the "Optional Subseq. Activities".

I have a link that takes me into the Runtime Workbench to a certain message and it looks like this:

http://servername:port/mdt/index.jsp?local=false&objectName=name=is.01.cat01135,type=XIServerEngine&messageid=8F2A2BFF034A40DF295C8DBA629F5810

So at the end there is the GUID of the message.

Now I would like that link in my alert and created the following:

http://servername:port/mdt/index.jsp?local=false&objectName=name=is.01.cat01135,type=XIServerEngine&messageid=&SXMS_MSG_GUID&

Please look at "=&SXMS_MSG_GUID&" at the end - I thought the message ID would automatically put there but it does not work!

Do you know how I have to make the link, so the GUID is at the end of my link in the alert?

Thank you!

Peter