How accurate is the plan matrix and availability?

I've tried to sign up for a Linode64, since the matrix shows that 4 are available. However, when I try to sign up for one, it reports to me that "no plan was found that could match your request. Please narrow your selection, and try again." I've emailed support@linode.com, but I thought I would ask on the forum as well… is the plan matrix accurate usually, or does this indicate a problem on my end (browser settings, etc)?