As this is a major point of misunderstanding when dealing with a new QueueMetrics installation, we creted a tutorial that explains step-by-step how to set up QueueMetrics in order to make use of the MySQL storage model and of clustering, as well.
The tutorial is called "Understading MySQL storage and clustering" and is immediately available for download on the downloads page, under "Misc Documentation" by the bottom of the page.
See
http://queuemetrics.com/download.jsp