Unexpected error connecting Report Viewer in MOSS WebPart page

If you plan to use Report Viewer WebPart (from SQL Server Reporting Services) in your WebPart pages dynamically (i. e. use this WebPart as connected WebPart - receiving Report Url): DO NOT FORGET TO INSTALL THE WP PACK GLOBALLY (-globalinstall option)!!!

Refer to: http://technet.microsoft.com/en-us/library/ms159772.aspx

STSADM.EXE -o addwppack -filename "C:\ Program Files\Microsoft SQL Server\90\Tools\Reporting Services\SharePoint\RSWebParts.cab" -globalinstall
Otherwise you will get always an unexpected error on exit edit mode.

Enjoy!