Affiliate plugin: Signups not being tracked anymore

I just realized that my affiliates are getting lots of hits, but none of the signups are being tracked.

I did a test signup and the click got tracked, but not the signup.

The only thing I've done was change the cookie length a while back, but I've been tracking affiliates and signs up in the meantime.

I changed it to this:

valid for 30 days.
@setcookie('affiliate_' . COOKIEHASH, 'aff' . md5(AUTH_SALT . $_GET['ref']), (time() + (60*60*24*365)), COOKIEPATH, COOKIE_DOMAIN);

Not sure how to check how the cookies get left in the browser.

Please help!