An easy way to test connectivity to your application is using Jconsole tool, execute the jconsole.exe file that is located in <SiteScope Folder>\java\bin
Then go to Remote Process option and write same URL you are using on JMX monitor.
If using Jconsole you cannot connect to this particular server, SiteScope can be ruled out as the problem, because JMX monitor is using the methods and techniques defined for the JMX API which is a Java Technology.
Both tools, SiteScope and for example Weblogic use it to communicate or connect because Java is the core language used to develop these applications.
Things to verify:
- IIOP configuration
- ports (are they correct, can the be reached, are they blocked by firewll)
- network issues, routing
- vlan restrictions