We are sorry for the inconveniences.
If this issue appeared after installing/reinstalling the product, please read this kb article on howto troubleshoot server installation issues:
http://support.softwarefx.com/Chart_FX_7/article/2501002#!7621036
To discard active client issues, please make sure to set the chart rendering method as an image.
If you are using PSS, please read the following kb articles on how to troubleshoot PSS issues:
http://support.softwarefx.com/Chart_FX_7/article/2501002#!7622021
http://support.softwarefx.com/Chart_FX_7/article/2501002#!7621013
If none of the above helped to fix the issue, then we are going to need a repro case: a simple web page rendering a single chart (do not pass any data to the chart) and also please send us the full rendered html of the problematic page.
Let us know about your findings.