If the update check reports an error for all bookmarks, then one of the following reasons may cause the problem:
Proxy settings are not correct
If you need a proxy to connect the internet, then you have to enter the proxy configuration in WebSite-Watcher.
Open "Program configuration..." in the Options menu
Select the "Check" tab
Click the "Proxy" button
Enter your proxy configuration
WebSite-Watcher is blocked by a Firewall
If you have a firewall running, then WebSite-Watcher is probably blocked by that firewall or another internet security tool. In that case you have to setup your firewall to let WebSite-Watcher pass, the problem cannot be fixed within WebSite-Watcher.