Thread:Project:Support desk/Thumbnails not shown for anonymous user (but only a part of them)/reply

Can enybady help ? Sthe strange thig is that i have one page that has one thumb in gallery that is visible for all and other not: http://encyklopedia.szczecin.pl/wiki/Szczecin_Gumie%C5%84ce In case of the single image the source of the page is:  Plik:Stacja Szczecin Niebuszewo 1.jpg
 * When user is logged in
 * When user is logged out

Is there any way to make thumbnails wisible for the anonymous users ?