Cannot Update Founder Pro

When I try to update the FounderPro plugin, from 1.19 to 1.21, I get the following message “An error occurred while updating Founder Pro: Update package not available.” Furthermore, on the WP update page, when I click “View Version 1.21 details,” the first time a popup shows with the details. But if I click again, I get another error message in the popup, “An unexpected error occurred. Something may be wrong with www.ads-software.com or this server’s configuration. If you continue to have problems, please try the support forums.”