OCM ocm:discriminator NodeType

[Edgar Merino]

Hello,

   I'm trying to get OCM running, however I'm encountering a problem 
when trying to register the ocm:discriminator nodetype:

<?xml version="1.0" encoding="UTF-8"?>

<nodeTypes xmlns:nt="http://www.jcp.org/jcr/nt/1.0"; 
xmlns:jcr="http://www.jcp.org/jcr/1.0"; 
xmlns:mix="http://www.jcp.org/jcr/mix/1.0";>
   <nodeType name="ocm:discriminator" isMixin="true">
       <supertypes>
           <supertype>nt:base</supertype>
       </supertypes>
       <propertyDefinition name="ocm:classname" requiredType="String"
           autoCreated="false" mandatory="true" onParentVersion="COPY"
           protected="false" multiple="false" />
   </nodeType>
</nodeTypes>

   I get the following exceptions:

org.apache.jackrabbit.core.nodetype.InvalidNodeTypeDefException: Invalid 
namespace reference in a node type definition       
Caused by: javax.jcr.NamespaceException: Unknown namespace prefix ocm.
       at 
org.apache.jackrabbit.core.nodetype.xml.AdditionalNamespaceResolver.getURI(AdditionalNamespaceResolver.java:86)
       at 
org.apache.jackrabbit.spi.commons.conversion.NameParser.parse(NameParser.java:116)
       at 
org.apache.jackrabbit.spi.commons.conversion.ParsingNameResolver.getQName(ParsingNameResolver.java:62)
       at 
org.apache.jackrabbit.spi.commons.conversion.DefaultNamePathResolver.getQName(DefaultNamePathResolver.java:61)
       at 
org.apache.jackrabbit.core.nodetype.xml.NodeTypeReader.getNodeTypeDef(NodeTypeReader.java:139)
       at 
org.apache.jackrabbit.core.nodetype.xml.NodeTypeReader.getNodeTypeDefs(NodeTypeReader.java:122)
       at 
org.apache.jackrabbit.core.nodetype.xml.NodeTypeReader.read(NodeTypeReader.java:69)
       ... 5 more

   However, I've already register the ocm namespace prefix, calling 
NamespaceRegistry#getURI("ocm") returns 
"http://jackrabbit.apache.org/ocm";. Am I missing something here?

Thanks in advance,
Edgar Merino