function submitUploadForm() {
	
  var fileExtension=document.getElementById('upload_file').value.substring(document.getElementById('upload_file').value.lastIndexOf(".")+1);
	
	
	var fileExtensionOk=false;
	
  // posible extensions
  allowedFileExtension = new Array("mp3");

  
  while(allowedFileExtension.length>0) {
  	
  	if(fileExtension.toLowerCase()==allowedFileExtension.pop()) fileExtensionOk=true;     	
  }
  
 	if(fileExtensionOk == false)	{
		// notice
		alert("please select a mp3-file for upload");
	}
	else {
		// send
		document.getElementById('upload_status_box').className="visible_thing";
		document.getElementById('upload_form').submit();
		document.getElementById('upload_form_box').className="invisible_thing";	
		// -----------
	}	
}