Libellés : Impossible de trier par la colonne "Libellés" en administration back-office

http://projet0.kosmos.fr/servlet/com.univ.datagrid.servlet.DatagridServlet?BEAN_RECHERCHE=libelleDatagrid&ID_REQUETE=e6d63a1e-fcd7-46b4-b03f-85d4711f733b&sEcho=2&iColumns=4&sColumns=&iDisplayStart=0&iDisplayLength=10&mDataProp_0=type&mDataProp_1=code&mDataProp_2=libelleParLangue&mDataProp_3=url&sSearch=&bRegex=false&sSearch_0=&bRegex_0=false&bSearchable_0=true&sSearch_1=&bRegex_1=false&bSearchable_1=true&sSearch_2=&bRegex_2=false&bSearchable_2=true&sSearch_3=&bRegex_3=false&bSearchable_3=false&iSortCol_0=2&sSortDir_0=asc&iSortingCols=1&bSortable_0=true&bSortable_1=true&bSortable_2=true&bSortable_3=false