I came accross this post, which seems to be the issue I am having, my question is how do you do the following to fix the problem?
You will need to be sure that the chart httphandler is served by the same machine, which served the page.
Posted on Feb 17, 2010
This is my reply to the bug report you have open:
The httphandler registration is different for IIS6 and IIS7. For IIS7 you need to add an additional registration in <system.webServer> section in your web.config file. You can fine more details in this help topic. We recommend removing the chart httphandler registration completely and using the link in the VisualStudio smart tag (check the second image in this help topic) -- it will register the httphandler correctly for both IIS6 and IIS7.
As for the web farm -- RadChart will work in web farm environment under certain conditions. It would be an issue if the page is served and therefore the chart image is generated by one machine and the next request for the image itself is served by another machine. Then this second machine will not be able to find the image. You will need to be sure that the chart httphandler is served by the same machine, which served the page.
Please, keep the correspondence in a single thread, so it easier for both you and us to follow it. Thanks.
the Telerik team