mime_content_type() sees .swf flash file as text/plain

Hello, I am querying uploaded files using the php function mime_content_type($file), passing the absolute path to the file in the $file var. The result I get back is "text/plain" which clearly isn't what I expected - or hoped for. Is this php related or could it be Apache's config missing something like "AddType application/x-Shockwave-Flash .swf" ? I have no access to Apache's config as the server is managed but I really would like to filter files based on mime type as opposed to file extensions - and also get to the bottom of it. Thanks, Bob