error when added to page

Oct 25, 2008 at 11:05 PM

The web part installs without errors in my environment.  It also activates without error.

But when I try to use it on any page it gives an error:
Unable to display this Web Part. To troubleshoot the problem open the Web page in a Windows SharePoint Services-compatible HTML editor such as Microsoft Office SharePoint Designer.

Why would this be happening?