I receive this error whenever I run my extraction from the command line, not in the Spoon UI.
Missing plugins found while loading a transformation
Step : Mo
You must run Kitchen from Kettle installation directory.
As written here:
http://wiki.pentaho.com/display/EAI/Kitchen+User+Documentation
Please make sure that you are positioned in the Kettle directory before running the samples below. If you put these scripts into a batch file or shell script, simply do a change directory to the installation directory