Problem uploading files other than text/plain ones

Hello guys I'm trying to do a simple task: upload files. However, when I try to upload files other than text/plain ones I get an empty $_FILES array. Is there anything I've got to modify in my php.ini file? I'm just following the expample in the php manual, the only thing different is that I process the upload task with a function: function upload_file($_POST, $_FILES) { //The same code as in the php manual return true; //If everything went ok } if (upload_file($_POST, $_FILES)) echo "The file has been uploaded"; else echo "Sorry, try again"; It works fine with text/plain files, so, am I overlooking anything here? Thanks a lot ******************************************************* Wilmar Pérez Network Administrator Library System Tel: ++57(4)2105962 University of Antioquia Medellín - Colombia 2002 *******************************************************