devo dare al varore $dir_upload il valore della scelta dei radio button... come posso fare? cosi mi da errore

Codice PHP:
<?php 
echo "<FORM  METHOD=\"POST\" NAME=\"contact_form\">
 <TABLE align=\"center\" >
 <TR>
 <TD >[b]<font color=\"blue\"><u>SCEGLI LA CARTELLA </u></font>[/b]

</TD></TR>
 <tr><TD>
  <input type=\"radio\" name=\"contact_type\" value=\"Contabile\">Area Contabile

        <input type=\"radio\" name=\"contact_type\" value=\"Dichiarazione\" checked>Area Dichiarazioni

        <input type=\"radio\" name=\"contact_type\" value=\"Altri_Documenti\" checked>Altri Documenti
</TD>
  </TR>
 </TABLE></FORM>";
$dir_upload=$_POST['contact_type']; 
 //DIRECTORY DOVE EFFETTUARE L'UPLOAD
$chmod_dir=0777; // PERMESSI DELLA DIRECTORY
$debug=0; // 1=STAMPA ALCUNE SEMPLICI INFORMAZIONI DI DEBUG, 0=NON STAMPARE
$sovrascrivi_file=0; // 1=SOVRASCRIVI I FILES SE ESISTENTI, 0=NON SOVRASCRIVERE I FILES
$dim_massima=500; // DIMENSIONE MASSIMA UPLOAD IN KB
define("DIM_MASSIMA",$dim_massima*1024);
$check_tipi=1; //1=CONTROLLA IL TIPO DI FILE, 0=NON CONTROLLARE
$tipi_permessi=array( //ARRAY PER ALCUNI TIPI DI FILE
    "text/plain",
    "text/html",
    "text/xml",
    "image/jpeg",
    "image/gif",
    "image/png",
    "video/mpeg",
    "audio/midi",
    "application/x-zip-compressed",
    "application/vnd.ms-excel",
    "application/x-msdos-program",
    "application/octet-stream",
    "application/pdf"
);

echo "<html>
        <head>
        <script type=\"text/javascript\" src=\"esterno.js\"></script>
        </head>
        <body>
        <form action=\"{$_SERVER['PHP_SELF']}\" method=\"POST\" name=\"modulo\" enctype=\"multipart/form-data\">
        <div id=\"attachment\" style=\"display:none\">
             <input id=\"file\" name=\"file\" type=\"file\" size=\"55\" />
             <a href=\"#\" onclick=\"javascript:removeFile(this.parentNode.parentNode,this.parentNode);\"> Rimuovi</a>
        </div>
        <div id=\"attachments\">
            
<a id=\"addupload\" href=\"javascript:addUpload('file')\">Aggiungi file</a>


            <input name=\"file[]\" type=\"file\" size=\"55\" />
            <span id=\"attachmentmarker\"></span>    
        </div>
        <input type=\"hidden\" name=\"MAX_FILE_SIZE\" value=\"".DIM_MASSIMA."\" />

        
        <input type=\"submit\" value=\"invia\" />
        </form>
        </body>
        </html>\n";
    
?>