Hi, i have a folder structure for pdf-files: - downloads\currentweek - downloads\nextweek

inside i have 1 pdf for menus. when i want to move the pdf-file from nextweek to currentweek, it doesn't work. but a image like png/jpg i can move. i got this error: The current node is not allowed under the chosen node because of its type

could you please help me why this dont work? it's not possible? a bug? or a config-setting is missing? i work with umbraco 8.18.0

thanks for your help and kind regards, Andy