[otrs] graph-pie not displayed in format selector when generating report

Hello all! I use reports and want to make selectable format for users: CSV, Print, graph-bars, etc. But when I select multiple options and one of them graph-pie - it not displayed later in list, all selected except graph-pie. If I select only this diagram will worked fine. Maybe this is bug or feature? :-) PS: OTRS 2.2.7 from Debian Lenny repos.