The Network Map is not Working – Zenoss

Dear Techie Guys, I wonder if you have encountered a similar error in Zenoss before. I have this problem just today in our Network Map (Zenoss). I have tried clicking it but only a gray background appeared. I cannot remember any configurations changes recently so I do not know what is the problem. Please tell me how can I fix this. Thank you very much in advance for some probable solutions that you can suggest.
