Hi,
Temporarily, you can do a manual update via the dlinkddns site and change your IP, but this will do nothing for you in the long run if it's not working reliably. I have had rare but periodic problems with dlinkddns not getting updated, but this is via their NAS devices. Luckily, IP's don't change as often as you might expect for most ISP's.
A longer lasting work around would be to install client software on a networked PC which you use the most. I am pretty sure the Dyndns software can be configured to update the dlinkddns service.
http://dyn.com/apps/update-client-faqs/