Jeroen,
All medication types are supported in PPE. But there seem to be a problem with the "View Things" link for the new medication type on the http://developer.healthvault.com/types/types.aspx page. I get the same error you get.
You may want to check out the versioning feature explained in the link below to understand how various medication types fit together.
http://blogs.msdn.com/ericgu/archive/2008/10/13/versioning-in-healthvault.aspx
Also, you can also check if the added medication types appears using developer tool
X-ray Raj
Raj
HealthVault Developer Tool
http://xray.getrealconsulting.com