I had to fix an issue today with cfchart and after dig deep on google and blogs I found this solution the only one that worked for us:
http://www.bpurcell.org/blog/index.cfm?entry=998&mode=entry
The issue is that the flash movie does not load or the image does not display when using the cfchart tag. Usually the problems is related to JRunScripts and graphdata.cfm.
If you need help drop a comment bellow.
