how to create Predecessor link in Scrum Templeate

I found in Scrum template, there is no Predecessor,but I really need it.

so I plan to use Plugin to create a new link type which called pre

in plugin, i add link extension and the plugin.xml like below:

<?xml version="1.0" encoding="UTF-8"?>
<?eclipse version="3.4"?>
<plugin>
   <extension
         point="com.ibm.team.process.service.operationAdvisors">
      <operationAdvisor
            class="advi.OperationAdvisor"
            id="advi.operationAdvisor"
            name="PATAC Advisor"
            operationId="com.ibm.team.workitem.operation.workItemSave">
         <extensionService
               componentId="advi.myExtensionService"
               implementationClass="advi.MyAbstractService">
                <prerequisites>
                   <requiredService interface="com.ibm.team.workitem.service.IWorkItemServer"/>
                   <requiredService interface="com.ibm.team.repository.service.IRepositoryItemService"/>
                   <requiredService interface="com.ibm.team.repository.service.IContentService"/>
                   <requiredService interface="com.ibm.team.workitem.service.IAuditableServer"/>
                   <requiredService interface="com.ibm.team.repository.common.service.IContributorService"/>
                   <requiredService interface="com.ibm.team.workitem.common.IWorkItemCommon"/>                  
                </prerequisites>
         </extensionService>
      </operationAdvisor>
   </extension>
   <extension
         point="com.ibm.team.repository.common.linkTypes">
      <linkType
            componentId="com.bim.team.linktype.component"
            constrained="true"
            id="com.ibm.team.linktype.pre"
            internal="false">
            <source>
                <endpoint
                    displayName = "Pre"
                    id = "pre_id"
                    multiplicity = "0..1">
                    <itemReferenceType
                        itemTypeName = "WorkItem"
                        packageURI = "com.ibm.team.workitem"/>
                </endpoint>
            </source>
            <target>
                <endpoint
                    displayName = "Pre By"
                    id = "pre_by_id"
                    multiplicity = "0..n">
                    <itemReferenceType
                        itemTypeName = "WorkItem"
                        packageURI = "com.ibm.team.workitem"/>
                </endpoint>
            </target>
      </linkType>
   </extension>
</plugin>

and then I restart the server

I can not found the new link type in Quick info presentation.

I think maybe my deployment is wrong .

so anyone knows how to do it?

thx