Perchè il W3C non mi valida questo form?

<FORM action=http://FormMail.aruba.it/cgi-bin/FormMail.pl method=post>
<input type=hidden name="recipient" value="info@diska.it">
<input type=hidden name="subject" value="Advise me for new photos">
<input type=hidden name="required" value="email">
<input type=hidden name="print_config" value="email">
<input type=text name="email" size="16" style="BACKGROUND: #FFFFFF; COLOR: #000080; FONT-FAMILY: Verdana; FONT-SIZE: 10pt"><input type=hidden name="missing_fields_redirect" value="http://www.diska.it/erroreuk.htm"><input type=hidden name="redirect" value="http://www.diska.it/rispuk.htm"><input type=SUBMIT value=" Go " name="SUBMIT" style="BACKGROUND: #8FBC8F; COLOR: #FFFFFF; FONT-FAMILY: Verdana; FONT-SIZE: 10pt">
</form>

Mi dice:
Line 127, column 6: end tag for element "FORM" which is not open
</form>

Grazie.