Hi Todor,

 Below is the sample I took from one or two of your posts to build the DataTable and dynamic type for that datatable which is then bound to Itemsource of the FlatDatasource.

private DataTable GetTable()
{
      //
      // Here we create a DataTable with four columns.
      //
      DataTable table = new DataTable();
      table.TableName = "Sales";
      table.Columns.Add("Dosage", typeof(double));
      table.Columns.Add("Drug", typeof(string));
      table.Columns.Add("Patient", typeof(string));
      table.Columns.Add("Date", typeof(DateTime));

      //
      // Here we add five DataRows.
      //
      table.Rows.Add(25.1, "Indocin", "David", DateTime.Now);
      table.Rows.Add(50, "Enebrel", "Sam", new DateTime(2011, 1, 1));
      table.Rows.Add(10, "Hydralazine", "Christoff", new DateTime(2011, 2, 2));
      table.Rows.Add(21, "Combivent", "Janet", new DateTime(2011, 3, 3));
      table.Rows.Add(100.2, "Dilantin", "Melanie", new DateTime(2011, 4, 4));
      return table;
}

private IEnumerable BuildItemsource(DataTable table)
{
      DynamicTypeBuilder typeBuilder = new DynamicTypeBuilder
      {
        DynamicAssemblyName = "MyAssembly",
        DynamicTypeName = "PatientInfo"
      };

 ... 
}

Here is the xaml defined the flatdatasource.

<FlatData:FlatDataSource x:Key="FlatDataSource"
                         ConnectionSettings="{StaticResource FlatDataConnectionSettings2}"
                         Cube="PatientInfo"
                         Rows="[Patient].[Patient]"
                         Columns="[Date].[Date]"
                         Measures="Dosage" 
                             >

        <FlatData:FlatDataSource.CubesSettings>
          <FlatData:CubeMetadata DataTypeFullName="PatientInfo" DisplayName="Patient Information">
            <FlatData:DimensionMetadata SourcePropertyName="Date" DisplayName="Visit Date"/>
            <FlatData:DimensionMetadata SourcePropertyName="Patient" DisplayName="Patient Name" />
            <FlatData:DimensionMetadata SourcePropertyName="Dosage" DisplayName="Dos Age" DisplayFormat="{}{0:C2}" />
          </FlatData:CubeMetadata>
        </FlatData:FlatDataSource.CubesSettings>

        <!--<FlatData:FlatDataSource.HierarchyDescriptors>
          <FlatData:HierarchyDescriptor SourcePropertyName="Date" HierarchyName="Visit Date" />
          <FlatData:HierarchyDescriptor SourcePropertyName="Patient" HierarchyName="Patient Name" />
        </FlatData:FlatDataSource.HierarchyDescriptors>-->

</FlatData:FlatDataSource>

Here is the screenshot when I run the my sample app.