That is because the value <VAL:LOCATION> that is being used by the email template only take into consideration managed systems within TMS. What I would do, and it's what I've done myself is change that value to <VAL:PARTCIPANT_NAME> which considers a particpant to be one of the following: video system, external dial in, phonebook entry, the name as stored in Cisco TMS.
Keep in mind if you change the values, you might also need to change the <FOREACH:...> value that surrounds it in the template so that it will repeat for each value that there is. Some values require something around it, such as a section, or foreach, etc.
Suggest you take a look at either the TMS admin guide or online help about email templates and what some of the tags are and can be put into what template, as some tags are template specific.
