CB Connector does not work with the Joomla! 1.5.x series.
Some of this reason is that it uses the xAjax Mambot which does not work in the J1.5.x series.
CB Connector v3 will be the first version to work in both the J1.0.x and J1.5.x series. Still in the design of this version so it may be a while until any betas are ready.