The Dreaded Subreport Could Not Be Shown Error

I seem to have run across the feared "Error: Subreport could not be shown" problem. I have very carefully checked everything I could find on the issue, but nothing seems to help--and I must admit, I'm at my wits' end here (though it's probably something absurdly simple).

I have a main report with one subreport. I am running ASP.NET, with a ReportViewer control on my ASPX page. The main report and subreport are both local reports, and pull data from SQL data sources.

Initially, I had the parent report pass a parameter to the subreport, but in the interest of keeping things simple I removed that--even though I verified that my handler for the subreport processing was valid and was obtaining valid values for the parameter.

Here's the applicable code from the CodeBehind's class:




Code Snippet



DataView vw;

protected void Page_Load(object sender, EventArgs e)
{
vw = (DataView)SqlDataSource2.Select(DataSourceSelectArguments.None);
rptAllCustomers.LocalReport.SubreportProcessing += new SubreportProcessingEventHandler(ProcessSubReports);
}

protected void ProcessSubReports(object sender, SubreportProcessingEventArgs e)
{
//vw.RowFilter = "SALES_INDEX = " + e.Parameters["SaleIndex"].Values[0];
e.DataSources.Add(new ReportDataSource("SALESConnectionString", vw));
}



And the applicable ASPX code:





Code Snippet

<rsweb:ReportViewer ID="rptAllCustomers" runat="server" Font-Names="Verdana"
Font-Size="8pt" Height="400px" Width="100%">
<!%--<localreport reportpath="App_GlobalResourcesSalesByProduct.rdlc">
</localreport>--%>
<localreport reportpath="App_GlobalResourcesBySale.rdlc"><datasources>
<rsweb:ReportDataSource DataSourceId="SqlDataSource1" Name="SalesData_SALES"></rsweb:ReportDataSource>
</datasources>
</localreport>
</rsweb:ReportViewer>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:sales %>"
SelectCommand="SELECT * FROM SALES WHERE SALE_DELETED = 'false'">
</asp:SqlDataSource>
<asp:SqlDataSource ID="SqlDataSource2" runat="server"
ConnectionString="<%$ ConnectionStrings:sales %>"
SelectCommand="SELECT * FROM CUSTOMER_PRODUCTS">
</asp:SqlDataSource>

Through debugging and other means, I have found the following:

1. The data being passed through vw in the ProcessSubReports is valid.
2. The subreport runs perfectly when placed into its own ReportViewer
3. The reports are all in the App_GlobalResources folder
4. The main report references a subreport by the name of SalesByProduct
5. App_GlobalResources/SalesByProduct.rdlc is the name of the report file

I should be able to provide more information on request.

Anyone have any clues?