First, make sure that you have the registration code or key that you received when you purchased the application. Now, try uninstalling and reinstalling the application, then check to see what version you have and update if necessary. In case you still didn't get the latest version make sure that you have a working Internet connection and that you're not blocking the application with your firewall. Finally, if you use a Proxy or VPN, try temporary disabling them and see if PowerDesk will finally update that way.
In case none of these solutions worked, the most plausible explanation is that the update hasn't started rolling out in your region yet. Try contacting the developers directly using one of the options on this page: http://www.avanquest.com/USA/group/contact/index.html and ask them for assistance with your problem.