What am I missing from the new work item link I've created?

I'm trying to create a custom link between work items, but once I have everything setup I can't actually select the new link type from the work item

I used this entry on DeveloperWorks as my starting point for creating the link
https://www.ibm.com/developerworks/community/blogs/extendingrtc/entry/newlink?lang=en

I've created the plug-in project for the link, plus the feature and update site projects.  I've installed the plug-in locally in my eclipse dev environment as well.

I can see the new link type when I edit my Links presentation.  I can also see the new link type in my queries.  What am I missing to actually be able to create the link?

Here's the code from plugin.xml
<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="com.ibm.team.repository.common.linkTypes">
      <linkType
            constrained="false"
            id="rtc_propagation_link.linkType.propagation"
            internal="false">
         <source>
            <endpoint
                  displayName="Propagate To"
                  id="propagateTo"
                  multiplicity="0..n">
               <itemReferenceType
                     itemTypeName="WorkItem"
                     packageURI="com.ibm.team.workitem">
               </itemReferenceType>
            </endpoint>
         </source>
         <target>
            <endpoint
                  displayName="Propagated From"
                  id="propagateFrom"
                  multiplicity="0..1">
               <itemReferenceType
                     itemTypeName="WorkItem"
                     packageURI="com.ibm.team.workitem">
               </itemReferenceType>
            </endpoint>
         </target>
      </linkType>
   </extension>
 
</plugin>