I have done the same and I restarted browser and my machine, and when I relogined to the application still the same message is appearing,
Sun Java Plug-in Required The Sun Java Plug-in must be installed on your local machine in order to run this workbench. The Sun Java Plug-in can be downloaded from the following directory: /dsworkbench/clientinstall Please contact your system administrator to verify the location of the client installations. Installing the Sun Java Plug-in, version 1.6.0_19 The Sun Java Plug-in is required to run the WebLogic version of this workbench. To install: Download the file jre-6u19-windows-i586.exe and execute it. On the license terms screen, select Custom setup and click Accept. If you want to change the default installation directory, click Change and specify a different directory. Once the installation directory is set, click Next. Click Next to accept the default browser registrations. Disabling Auto-Update Capability By default, the Java Control Panel is configured to automatically download and update to newer releases of the Java Plug-in as they become unavailable. It is advisable to turn off this feature so that compatibility between the Java Plug-in and the workbench is maintained. To turn off automatic updates: Open the Windows Control Panel, and click Java. The Java Control Panel displays. Click the Update tab. Under the Update Notification area, deselect Check for Updates Automatically. "Java Update - Warning" dialog box displays. Click Never Check. Click OK to save and then close the Java Control Panel.