Kan ikke kalde Javascript med onSubmit()

Jeg har en loginside i ASP, der bruger MD5-kryptering, men jeg kan ikke kalde min encrypt()-funktion.
----kode start-----
<script language="JavaScript" type="text/javascript" src="include/md5.js"></script>
<script language="javascript">
function encrypt() {
    // identify if a session cookie was given, otherwise logout
    // cookieStr = document.cookie;
    // session cookie exists, so we can go ahead and encrypt
    session_id = "<% = Session.SessionID %>";
    str = document.fform.pass.value + "*" + session_id;
    document.fform.pass.value = "";
    document.fform.response.value = MD5(str);
    document.fform.submit();
}
</script>
<script language="javascript">
function submitit() {
    if (window.event.keyCode==13) {
    encrypt();
    return false;
        }
}
</script>
      <h1>Password protected website</h1>
      <h4>This site is for authorized visitors
        only. In order to log in, session cookies must be enabled on your PC.</h4>
      <form name="fform" method="post" action="check_pw.asp" onSubmit="encrypt();">
        <p> Login:<br>
          <input type="text" name="txtUserName">
        <p>Password:<br>
          <input type="password" name="pass" id="pass">
          <input type="submit" value="Submit">
      </form>
-------kodeslut---------
Er det forkert brug af onSubmit eller hva?