htmlarea.js error

Clean Drupal 4.6.3 installation, with htmlarea module and xinha added and enabled. Pages with textareas do not display htmlarea and return the following error:

Error: HTMLArea.checkSupportedBrowser is not a function
Source File: http://wvnorml.org/modules/htmlarea/xinha/htmlarea.js
Line: 81

This reproduces on every browser I have available, htmlarea on other sites displays properly in same browsers.