FlexPMD view always empty (Flex Builder 4.5.1 in Eclipse 3.6.2 on 32bit WinXP)

I've installed the v1.2 all in one .zip and configured it as per http://opensource.adobe.com/wiki/display/flexpmd/FlexPMD+Eclipse+plugin after installing the plugin itself some time ago (back in v1.1 days). No updates are show right now as pending and the update site is enabled.

Although the CPD detector runs OK, when I right click a source folder and choose 'Run FlexPMD', the Flex PMD view remains empty. The PMD builder is enabled for the project too, no joy.

The eror log doesn't have anthing relevent, just :

eclipse.buildId=M20110210-1200

java.version=1.6.0_26

java.vendor=Oracle Corporation

BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=en_GB

Command-line arguments:  -os win32 -ws win32 -arch x86

Error

Wed Jan 04 14:20:20 GMT 2012

Unable to create menu item "com.adobe.ac.pmd.eclipse.toolbar.runCommand", command "com.adobe.ac.pmd.eclipse.flexpmd.runCommand.category" not defined

Any hints ?