I had the same problemthe same problem.
On the Server load terminal.app in your Utilities folder, and type in:
On Mountain Lion:
sudo defaults write /Library/Server/Wiki/Config/collabd.plist FiltersEnabled false
On Lion:
sudo defaults write /etc/collabd/collabd.plist FiltersEnabled false
You may need to turn the Wiki Service off and on afterward for the settings to take affect. You can do this by typing:
sudo serveradmin stop wiki
then
sudo serveradmin start wiki
in the Terminal.
