Resize picture

Har fået denne kode, men der sker ingen ting. Jeg for ingen fejl koder, eller noget som tyder på noget forkert.
Men der kommer heller ikke noget billed:

$mappe = billed/mave/
$newfilename = ugeXX_1.jpg
Mappe/Filnavn efter udførelse: "billed/mave/ugeXX_1b.jpg"

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<?
$sourcefile = "$mappe . $newfilename";
$dest_x  = "193";
$dest_y  = "145";
$targetfile = "$mappe . $uge . '_1b' . $file_ext";
$jpegqual  = "100";

function resizeToFile ($sourcefile, $dest_x, $dest_y, $targetfile, $jpegqual)
{

/* Get the dimensions of the source picture */
$picsize=getimagesize("$sourcefile");
$source_x = $picsize[0];
$source_y  = $picsize[1];
$source_id = imageCreateFromJPEG("$sourcefile");

/* Create a new image object (not neccessarily true colour) */
$target_id=imagecreatetruecolor($dest_x, $dest_y);

/* Resize the original picture and copy it into the just created image
  object. Because of the lack of space I had to wrap the parameters to
several lines. I recommend putting them in one line in order keep your
  code clean and readable */
$target_pic=imagecopyresampled($target_id,$source_id,0,0,0,0,$dest_x,$dest_y,$source_x,$source_y);

/* Create a jpeg with the quality of "$jpegqual" out of the
  image object "$target_pic".
  This will be saved as $targetfile */
imagejpeg ($target_id,"$targetfile",$jpegqual);
return true;
}
?>