getting my spf record correctly

My spf record was working fine. However some time ago my ISP changed names and with it the names of their smtp servers.

My mailserver is at home, my ISP is online.nl, My mailserver relays via smtp.online.nl.
My domain is geerdes.nl, my nameservers are hosted by zoneedit.com
When I sent a mail, I can see that they are sent by smtp01.online.nl or smtp02.online.nl etc  (don't know how
many they have but at least 10).
my spf record is currently set up like this:

geerdes.nl. IN TXT "v=spf1 a:smtp01.online.nl a:smtp02.online.nl a:smtp03.online.nl
a:smtp04.online.nl a:smtp05.online.nl a:smtp06.online.nl a:smtp07.online.nl
a:smtp08.online.nl a:smtp09.online.nl a:smtp10.online.nl

When I sent a mail to auth-results <at> verifier.port25.com it returns a mail with 'pass'

If I send it to spf-test <at> openspf.org it returns:

Mail Delivery System [MAILER-DAEMON <at> smtp02.online.nl]

Your message did not reach some or all of the intended recipients.

      Subject:

The following recipient(s) cannot be reached:

      spf-test <at> openspf.org on 13-6-2009 0:11
            mailout02.controlledmail.com: Failed (550 5.7.1 <spf-test <at> openspf.org>: Recipient address   
rejected: SPF Tests: Mail-From Result)

So what could be still wrong?

Tnx

  Ben