I'm trying to bind the UltraWebtree to a WebHierarchicalDataSource using 2 sqldatasources. Practically I'm, following the sample of the sample website. (http://samples.infragistics.com/2008.2/webfeaturebrowser/WebHierarchicalDataSource/UltraWebTreeBinding.aspx)

I'm getting this error

Please verify that the DataFile or Data property has been set on the XMLDataSource.

[Exception: Please verify that the DataFile or Data property has been set on the XMLDataSource.]
   Infragistics.WebUI.UltraWebNavigator.UltraWebTree.BindTopLevelNodes(Node node, String nodeId) +448
   Infragistics.WebUI.UltraWebNavigator.UltraWebTree.PerformDataBinding() +584
   System.Web.UI.WebControls.HierarchicalDataBoundControl.PerformSelect() +85
   System.Web.UI.WebControls.BaseDataBoundControl.DataBind() +73
   System.Web.UI.WebControls.BaseDataBoundControl.EnsureDataBound() +82
   System.Web.UI.WebControls.BaseDataBoundControl.OnPreRender(EventArgs e) +22
   Infragistics.WebUI.UltraWebNavigator.UltraWebTree.OnPreRender(EventArgs e) +38
   System.Web.UI.Control.PreRenderRecursiveInternal() +80
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Control.PreRenderRecursiveInternal() +171
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +842

What's wrong here ?