Own DataFormWebPart: Unable to display this Web Part

Unable to display this Web Part. To troubleshoot the problem, open this Web page in a Microsoft SharePoint Foundation-compatible HTML editor such as Microsoft SharePoint Designer. If the problem persists, contact your Web server administrator.

The webpart is in PageLayout, inserted without webpartzone:

<MyWebParts:MyCustomWebPart runat="server" Description=""
ListDisplayName="" PartOrder="2" HelpLink="" AllowRemove="True"
IsVisible="True" AllowHide="True" UseSQLDataSourcePaging="True"
ExportControlledProperties="True" DataSourceID="" Title="" ViewFlag="0"
NoDefaultStyle="TRUE" AllowConnect="True" FrameState="Normal"
PageSize="10" PartImageLarge="" AsyncRefresh="True" ExportMode="All"
Dir="Default" DetailLink="" ShowWithSampleData="False" FrameType="None"
PartImageSmall="" IsIncluded="True" SuppressWebPartChrome="False"
AllowEdit="True" ManualRefresh="False" ChromeType="None"
AutoRefresh="False" AutoRefreshInterva开发者_如何转开发l="60" AllowMinimize="True"
ViewContentTypeId="" InitialAsyncDataFetch="False"
MissingAssembly="Cannot import this Web Part." HelpMode="Modeless"
ListUrl="" ID="g_c2180fb9_c667_42f3_aab3_c3340cb0ac5a"
ConnectionID="00000000-0000-0000-0000-000000000000"
AllowZoneChange="True" IsIncludedFilter=""
__MarkupType="vsattributemarkup"
__WebPartId="{C2233FB9-C667-42F3-AAB3-C334223C5A}"
__AllowXSLTEditing="true" WebPart="true" Height="" Width="">
<Xsl>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" version="1.0" encoding="UTF-8" indent="yes"/>
  <xsl:template match="/">
    <xmp>
      <xsl:copy-of select="*"/>
    </xmp>
  </xsl:template>
</xsl:stylesheet>
 </Xsl>
<DataSources>
<SharePoint:SPDataSource runat="server" DataSourceMode="List"
SelectCommand="<View></View>" UpdateCommand=""
InsertCommand="" DeleteCommand="" UseInternalName="True"
ID="spdatasource3">
<SelectParameters>

<asp:Parameter DefaultValue="0"
Name="StartRowIndex"></asp:Parameter><asp:Parameter DefaultValue="0"
Name="nextpagedata">
</asp:Parameter><asp:Parameter DefaultValue="10"
Name="MaximumRows"></asp:Parameter>
</SelectParameters>


</SharePoint:SPDataSource>
</DataSources>
</MyWebParts:MyCustomWebPart> 

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I will give you 3 suggestions:

1. Implement error handling. At least by encapsulate you code in a try/catch block. Output the error to something like a Literal object in your web part.
2. Attach your Visual Studio debugger to the IIS process. Set a breakpoint in your constructor or load method and step through your code from there.
3. Look in the WSS log files to see if it says something of interest.

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The problem was missing resourceId and secondly i disabled cache-ing on xmlDataSource variable because it showed always the same results but queries were different

Now problem is paging - in MyWebParts:MyCustomWebPart you see PageSize, I set it to 1 but I see 5 items on my list - whats wrong? Is my XMLDataSource wrong somehow?

Moreover - is it possible to convert what is written above (MyWebParts:MyCustomWebPart) to .webpart file so that it could be reusable on othere pageLayouts .. ?

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I have noticed that you have the PageSize set to 10 in the initial MyWebParts:MyCustomWebPart and in the SharePoint:SPDataSource you have an entry

<asp:Parameter DefaultValue="10" Name="MaximumRows"/>

Try setting the SPDataSource value to 1.

Jonathan