Having all the appropriate credentials does not guarantee that you can use an application to manage every system within the application's scope of operation. Each system that you administer by using the Java Web Console application has its own security domain. Having read-and-write permissions on the web console system does not guarantee that those credentials are automatically sufficient to administer any other remote system.
In general, access to remote systems depends on how the security is implemented in the web application. Typically, web applications make calls to agents that perform actions on behalf of the applications. These applications must be authenticated by the agents based on their web console credentials and the credentials by which they are known on the agent system. Depending upon how this agent authentication is done, an authorization check might also be made on the agent itself, based upon this authenticated identity.
For example, in web applications that use remote WBEM agents, authentication typically uses the user or role identity that initially authenticated to the Java Web Console. If this authentication fails on that agent system, access to that system is denied in the web application. If authentication succeeds on that agent system, access might still be denied if the agent makes an access control check and denies access there. Most applications are written so that the authentication and authorization checks on the agent never fail if you have been successfully authenticated on the web console and assumed the correct role.