org.apache.maven.BuildFailureException: No SCM URL was provided to perform the release from

I'm using Maven 2.2.1 and I sucessfully ran:

mvn -B release:clean release:prepare

But get the error message:

No SCM URL was provided to perform the release from

when I run:

mvn release:perform

My pom.xml have the scm tags defined correctly:

<scm>
    <url>file:///C:/tmp/svnrepo/myproj/trunk</url>        
    <connection>scm:svn:file:///C:/tmp/svnrepo/myproj/trunk</connection>
    <developerConnection>scm:svn:file:///C:/tmp/svnrepo/myproj/trunk</developerConnection>        
</scm>