I tried to place 4 mschart controls on the same page but it is giving me major grief. Each chart appears properly when I place one per page, but as soon as I place multiple the first two are displaying incorrect data and the last two do no display anything at all.
I made sure that I am not using the same session variable eventhough that seems to be the most like culprit.
I resolved the issue by placing each chart in its own IFrame.