Chart control issue within another page

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ASP.NET

I have a webpage that works fine using the asp:charts control. Works fine on its own.
I then created a dashboard and used an iFrame inside. When I use the URL from the charts web page inside the iframe, it says

Failed to load resource: the server responded with a status of 404 (The image is not found.)  ChartImg.axd:1

I know it works because when I call the URL that is inside the iframe, it displays perfectly.
I know this used to work but for some reason, it does not.

Anyone else have this issue?
Thanks in advance.

What I have tried:

Tried putting the chart stuff in the web config of the dashboard. Did not work either.