submit help

   Need a little hand holding here. I've a site which wants a submit like:

<input name="cmd_login" class="loginbutton" id="cmd_login" value="Log in"
    onclick="check_mode(event); checkaddress();" tabindex="3" type="submit">

    A simple curl works:

curl -A "Mozilla/5.0" \
    -d "username_ex=<redacted>" \
    -d "password=<redacted>" \
    -d "interface_ex=html&cmd_login=Log In" \
    http://webmail.manynet.net/surgeweb

But adding "interface_ex=html&cmd_login=Log In" does not work.

Unrelated but has anybody seen a:

Handler function NM_observeActivity threw an exception: TypeError: aChannel.loadInfo is null

While processing a response?