Joomla 1.5 has not yet had a stable release. JoomlaKB is known not to work on Release Candidate 3 of Joomla 1.5 as JoomlaKB relies on bug fixes and code changes in Joomla 1.5 post-RC3. JoomlaKB is developed on, and tested with the SVN version of Joomla 1.5 only. We will ensure compatibility with the nightly SVN and with the final stable release version of Joomla 1.5. JoomlaKB will not work on Joomla 1.5 RC1, RC2 or RC3. Until Joomla 1.5 is released as stable, JoomlaKB (which depends on J1.5 code) will also remain in beta version.