Newbie question

I am new to OAT but I have encountered a problem. Everything was working fine BUT My performance charts stopped collecting data? See attached. They go to zero and stay there. Also the report on chunk I/O shows all zeros. Basically a lot of things I want to look at used to work but seem to have stopped working. Now I do not know how this thing works but it looks like it has historical data from prior to me setting up OAT. So it the data stored in an Informix table or is it saved on the front end that has the web server? I do have the ability to see data with onstat so I can see how things are working but I kinda liked the OAT graphs. Thoughts? Tim Ertl 413-442-9000 x6211