I created a new skin object, Current Time Skin Object, in VS2008 for DNN6 following the procedures outlined in the Wrox Professional DotNetNuke Module Programming book.

But, when I try to put it in my skin, I get the error: 'dnn' is not a valid value for attribute 'tagprefix'.

I think I did everything correctly but I can't understand why that error is showing, there are other lines in the file where TagPrefix="dnn".

One more bump because I'm frustrated with lack of help on this.

ViewCurrentTimeSkinObject.ascx.cs:
using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Web.UI;
using System.Web.UI.WebControls;
using DotNetNuke.UI.Skins;
using DotNetNuke.Services.Localization;

namespace SCIC.Modules.CurrentTimeSkinObject
{
    public partial class ViewCurrentTimeSkinObject : SkinObjectBase
    {
        #region Private members
            private bool _dateOnly = false;
            private const string _myFileName = "ViewCurrentTimeSkinObject.ascx";
        #endregion

        #region Public properties
            public bool DateOnly
            {
                get { return _dateOnly; }
                set { _dateOnly = value; }
            }
        #endregion

        protected void Page_Load(object sender, EventArgs e)
        {
            // Get template
            string templateText = Localization.GetString("DisplayTemplate", Localization.GetResourceFile(this, _myFileName));

            // Load Proper format
            if (_dateOnly)
                templateText = templateText.Replace("[TODAY]", System.DateTime.Now.ToShortDateString());
            else
                templateText = templateText.Replace("[TODAY]", System.DateTime.Now.ToString());

            // Load to User
            litContent.Text = templateText;
        }
    }
}

ViewCurrentTimeSkinObject.ascx.designer.cs:
//------------------------------------------------------------------------------
// <auto-generated>
//     This code was generated by a tool.
//     Runtime Version:2.0.50727.4961
//
//     Changes to this file may cause incorrect behavior and will be lost if
//     the code is regenerated.
// </auto-generated>
//------------------------------------------------------------------------------

namespace SCIC.Modules.CurrentTimeSkinObject {
    
    
    public partial class ViewCurrentTimeSkinObject {
        
        /// <summary>
        /// litContent control.
        /// </summary>
        /// <remarks>
        /// Auto-generated field.
        /// To modify move field declaration from designer file to code-behind file.
        /// </remarks>
        protected global::System.Web.UI.WebControls.Literal litContent;
    }
}
CurrentTimeSkinObject.dnn
<dotnetnuke version="3.0" type="Module">
  <folders>
    <folder>
      <name>SCIC.CurrentTimeSkinObject</name>
      <friendlyname>CurrentTimeSkinObject</friendlyname>
      <foldername>CurrentTimeSkinObject</foldername>
      <modulename>SCIC.CurrentTimeSkinObject</modulename>
      <description>A CurrentTimeSkinObject module</description>
      <version>01.00.00</version>
      <businesscontrollerclass>SCIC.CurrentTimeSkinObject.Components.CurrentTimeSkinObjectController</businesscontrollerclass>
      <modules>
        <module>
          <friendlyname>CurrentTimeSkinObject</friendlyname>
          <cachetime>0</cachetime>
          <controls>
            <control>
              <src>/nadnn/CurrrentTimeSkinObject/CurrentTimeSkinObject/App_LocalResources/ViewCurrentTimeSkinObject.ascx</src>
              <type>View</type>
              <helpurl></helpurl>
            </control>
          </controls>
        </module>
      </modules>
      <files>
        <file>
         <name>CurrentTimeSkinObject.dll</name>
    </file>
        <file>
          <name>ViewCurrentTimeSkinObject.ascx</name>
        </file>
        <file>
          <path>App_LocalResources</path>
          <name>ViewCurrentTimeSkinObject.ascx.resx</name>
        </file>
      </files>
    </folder>
  </folders>
</dotnetnuke>

Need anything else?