Hvorfor virker validering af e-mail formen ikke

Hej
Er der nogen der kan se hvad der ikke passer i dette script.
Mener selv at det hele skulle være i orden.

<script language="JavaScript">
<!--
function valider() {

    var errorMsg = "";


if (document.newtag.email.value.match(/^[a-z0-9_\.]+@[a-z0-9_\.]+\.\w{2,4}$/i)) {
            errorMsg += "\n\tEmail \t\t- Angiv en rigtig emailadd.";
    }
   
   
    //Fejlbeskrivelse
    if ((errorMsg != "")){
        msg = "_________________________________________________\n\n";
        msg += "Din email er ikke blevet tilføjet \n";
        msg += "_________________________________________________\n\n";
        msg += "\n";
       
        errorMsg += alert(msg + errorMsg);
        return false;
    }
   
    if (errorMsg == 0) {
   
    document.newtag.submitbutton.disabled = true;
   
    }
   
    return true;
}
// -->
</script>

</body>

<%
email = Trim(Request.Form("email"))

If Len(email) = 0 Then
%>
<br>
<BASEFONT FACE="verdana">
<TABLE BORDER="0" WIDTH="100%"><TR>
    <div align="center">
<%
response.write "<font size=2 face=Verdana, Arial, Helvetica, sans-serif><b>Indtaste din email adresse</b></font>"
%>
      <form method="POST" action="nybruger.asp" NAME="newtag" onsubmit="return valider()"> 
        Emailadresse: <input type="text" name="email" size="20" value="<% =email %>">
        <br><br>
          <Input  CHECKED type="radio" name="valg" value="1">
          Tilmeld
          <Input type="radio" name="valg" value="2">
          Afmeld
          <br><br>
          <input type="submit" value="Send" name="submitbutton">
 
      </form>
  </div> 
</TR>
</table>

<%
Else

if Request.Form("valg") = "1" then

Set Conn = Server.CreateObject("ADODB.Connection")
Conn.Open "PROVIDER=MSDASQL;DRIVER={Microsoft Access Driver (*.mdb)};DBQ=" & Server.MapPath("mail.mdb") & ";UID=admin;PWD=;"
Set rs = Server.CreateObject("ADODB.RecordSet")
strSQL = "SELECT * FROM mail WHERE email='" & email & "'"
rs.Open strSQL, Conn, 1, 3
if rs.EOF then
rs.AddNew
rs("email") = email
rs.Update
rs.Close
Set rs = Nothing
Conn.Close
set Conn = Nothing
%>

<TABLE BORDER="0" WIDTH="100%">
    <TR><div align="center"><br>
        <% response.write "<font size=2 face=Verdana, Arial, Helvetica, sans-serif><b>Du er nu optaget på mailinglisten</b></font>" %>
          </div>
  </TR>
</table>