Telerik RadHtmlChart Pie Chart Error - telerik

Question

I am attempting to use the RadHtmlChart pie chart, but I'm getting the following error:
Cannot create an object of type 'System.Nullable from its string representation 'StatCount' for the 'Y' property.
If I use the same SqlDataSource for an asp:Chart it works as expected. So my guess is that is this specific to the RadHtmlChart - but it's just a guess.
The query (MS SQL Server 2012) returns the following:
+----------------------+-----------------+
| stat | StatCount |
+----------------------+-----------------+
| Closed | 4067 |
+----------------------+-----------------+
| Pending Assignment | 1 |
+----------------------+-----------------+
| QA Ready | 600 |
+----------------------+-----------------+
| In QA | 400 |
+----------------------+-----------------+
| Assigned | 4946 |
+----------------------+-----------------+
Here's the SqlDataSource I'm using to get this data:
<asp:SqlDataSource
ID="sdsAssnmtStats"
runat="server"
ConnectionString='<%$ ConnectionStrings:DefaultConnection %>'
SelectCommand="SELECT s.stat ,cast(case s.stat when 'Pending Assignment' then count(a.clmNo) when 'Assigned' then count(a.clmNo) when 'QA Ready' then count(a.clmNo) when 'In QA' then count(a.clmNo) when 'Closed' then count(a.clmNo) else 0 end as nvarchar) as StatCount FROM assnmts a inner join assnmtStats astats on a.assnmtIdPk = astats.assnmtIdFk inner join stats s on astats.aStatId = s.statIdPk inner join repAssnmts ra on a.assnmtIdPk = ra.assnmtIdFk inner join aspnetusers anu on ra.repId = anu.Id inner join clients c on a.clientIdFk = c.clientIdPk inner join carrs on a.carrierId = carrs.carrIdPk inner join (SELECT a2.assnmtIdPk, MAX(astats2.asCrtdDt) as MaxDate FROM assnmts a2 INNER JOIN assnmtStats astats2 on a2.assnmtIdPk = astats2.assnmtIdFk GROUP BY a2.assnmtIdPk) mdt on a.assnmtIdPk = mdt.assnmtIdPk and astats.asCrtdDt = mdt.MaxDate inner join (select a3.assnmtIdPk, MAX(ra2.raCrtdDt) as MaxRepDate from assnmts a3 inner join repAssnmts ra2 on a3.assnmtIdPk = ra2.assnmtIdFk group by a3.assnmtIdPk) mrepdt on a.assnmtIdPk = mrepdt.assnmtIdPk and ra.raCrtdDt = mrepdt.MaxRepDate group by s.stat">
</asp:SqlDataSource>
Here's the RadHtmlChart:
<telerik:RadHtmlChart runat="server" ID="rhc_assnmtStats" Transitions="true" Skin="Default" DataSourceID="sdsAssnmtStats" >
<PlotArea>
<Series>
<telerik:PieSeries StartAngle="90">
<LabelsAppearance Position="OutsideEnd"></LabelsAppearance>
<SeriesItems>
<telerik:PieSeriesItem Exploded="true" Name="stat" Visible="true" VisibleInLegend="true" Y="StatCount" />
</SeriesItems>
</telerik:PieSeries>
</Series>
</PlotArea>
<Legend>
<Appearance Position="Right" Visible="true"></Appearance>
</Legend>
<ChartTitle Text="Assignment Counts by Status">
<Appearance Align="Center" Position="Top"></Appearance>
</ChartTitle>
</telerik:RadHtmlChart>
Here's the asp:Chart markup I used that works as expected:
<asp:Chart ID="assnmtStats" runat="server" DataSourceID="sdsAssnmtStats">
<Titles>
<asp:Title Font="Times New Roman, 14pt, style=Bold, Italic" Name="AssnmtStatsTitle" Text="Assignment Counts by Status"></asp:Title>
</Titles>
<Series>
<asp:Series Name="Series1" ChartType="Pie" XValueMember="stat" YValueMembers="StatCount" YValueType="Int32" Legend="assnmtStatsLegend" IsValueShownAsLabel="true"></asp:Series>
</Series>
<ChartAreas>
<asp:ChartArea Name="assnmtStatsChartArea" Area3DStyle-Enable3D="true"></asp:ChartArea>
</ChartAreas>
<Legends>
<asp:Legend Name="assnmtStatsLegend" Alignment="Center"></asp:Legend>
</Legends>
</asp:Chart>
What do I need to do to get the RadHtmlChart to work?
This is an ASP.net C# WebForms application I'm creating in Visual Studio 2017.

Answer 1

I received a solution from Telerik. I hope this helps anybody else who has trouble translating the demo on their site from a bar chart to a pie chart.
When data binding the chart series you need to set its DataFieldY property to point to the field name you want to use instead of populating its SeriesItems collection.
Here's the working solution:
<telerik:RadHtmlChart runat="server" ID="rhc_assnmtStats" Transitions="true" Skin="Default" DataSourceID="sdsAssnmtStats" >
<PlotArea>
<Series>
<telerik:PieSeries StartAngle="90" NameField="stat" DataFieldY="StatCount">
<LabelsAppearance Position="OutsideEnd"></LabelsAppearance>
</telerik:PieSeries>
</Series>
</PlotArea>
<Legend>
<Appearance Position="Right" Visible="true"></Appearance>
</Legend>
<ChartTitle Text="Assignment Counts by Status">
<Appearance Align="Center" Position="Top"></Appearance>
</ChartTitle>
</telerik:RadHtmlChart>