Thomas,

I am trying to use the Folder Picker and installing as described, but when I create the new Data type and choose TH.FolderPicker as the Render Control and then choose Save I immediately get an Object reference not set to an instance of an object error. The stack trace is as follows:

[NullReferenceException: Object reference not set to an instance of an object.]
   TH.FolderPicker.ExtensionMethods.GetWebFolder(TreeNode node) +32
   TH.FolderPicker.PrevalueEditor.Save() +174
   umbraco.cms.presentation.developer.editDatatype.save_click(Object sender, ImageClickEventArgs e) +31
   System.Web.UI.WebControls.ImageButton.OnClick(ImageClickEventArgs e) +108
   System.Web.UI.WebControls.ImageButton.RaisePostBackEvent(String eventArgument) +118
   System.Web.UI.WebControls.ImageButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565

I am using umbraco v 4.0.2.1, Windows 7, Firefox 3.5.5, IIS 7 and Asp.net 3.5. The same happens in Internet Explorer.

I suspect that the tree node is null, because I have had no opportunity to select a node because no treeview has appeared when I chose the TH.FolderPicker as the Render Control. I can't remember if this was always the case in Umbraco, but when choosing any control to render, specific properties of the control are not displayed until after the Save button is pressed and datatype is saved and re-rendered.

Any suggestions on why this is happening and what I can do about it?

Regards,
Brian.