Hi Tariq,
Your enterprise manager is offline. You need to start it up. Normally it happens when the load on Enterprise manager is high. It will be available in log located at /usr/sap/ccms/apmintroscope/logs
If the number of agents connecting to enterprise manager are increase try increasing the xmx for enterprise manager using the standard "/usr/sap/ccms/apmintroscope/Introscope_Enterprise_Manager.lax" file. Search for xmx string and increase the value to say "-Xms512m". To make java em memory consistent all the time we put "-Xms512m -Xmx512m" so java memory stays same all the time.
If you happen to see enterprise manager go down often consider this.
Best Wishes,
Giridhara