Realtime issue - not displaying realtime info/box

[jagarcia233]

Whenever i click on the Realtime plugin to the right of each graph i get the following error "The image Cache Director is not writable. Please set permissions and then attempt to open another realtime graph:. This has worked for the past two years and it just stopped working all of a sudden. I have tried rebuilding the poller cache but it did not fix the issue. I have also set the permissions for the realtime directory to 777 and this still did not fix the issue. Help Please