Web garden - first time the page loads only one chart appears

Question

I have a page with 2 charts in a web garden(it's a sharepoint application).  The charts are created programmatically in the Page Load ethod of a custom webpart.  Originally we had issues with charts appearing and disappearing but I have changed
the config setting to the following and both charts appear most of the time:
   <add key="ChartImageHandler" value="storage=file;timeout=20;dir=C:\inetpub\wwwroot\wss\VirtualDirectories\Myweb\uploadertemp\;" />
The problem I'm having is that the first time a user views the page only one of the charts appears.  If i navigate away and return to the page both charts appear.  Is there and issue with my config settings that is causing this behaviour?
Thanks
Karen 

Answer 1

The answer to this (after months of toying with settings and permissions) is not to user the chart control in a web garden.  I have seen the same issue multiple times on-line, with no concrete solution offered .
My workaround is to save the chart to a memory stream and write it to the page as an image, not as a chart control:
Chart chart = new Chart();
//Add data and chart settings here........
using (var chartStream = new MemoryStream())
chart.SaveImage(chartStream, ChartImageFormat.Png);
System.Web.UI.WebControls.Image chartImage =
new System.Web.UI.WebControls.Image();
chartImage.ImageUrl =
"data:image/png;base64," + Convert.ToBase64String(chartImage.GetBuffer());
chartParentControl.Controls.Add(chartImage);