title: has a SelectedValue which is invalid because it does not exist in the list of items. How do you debug?
body: <p>I am having problems with asp.net binding to a dropdownlist and I have no clue on how to debug. I checked out the other questions about this on stack but nothing has helped. As far as I can see the "name" it should select is in the list. </p>
  
  <pre><code>&lt;asp:DropDownList ID="dd1" runat="server" DataSourceID="ADataSource" DataTextField="Name" 
                                                      DataValueField="Name" SelectedValue='&lt;%# Bind("Name") %&gt;'   Width="255" 
                                                      AppendDataBoundItems="true" TabIndex="3"  Font-Size="small"  EnableViewState="true"    &gt;
                                               &lt;asp:ListItem Text="Select"  Value="" /&gt;
                                             &lt;/asp:DropDownList&gt;
  </code></pre>
  
  <p>Following is the error</p>
  
  <blockquote>
    <p>System.ArgumentOutOfRangeException was unhandled by user code
          Message='dd1' has a SelectedValue which is invalid because it does not exist in the list of items.
        Parameter name: value
          Source=System.Web
          ParamName=value
          StackTrace:
               at System.Web.UI.WebControls.ListControl.PerformDataBinding(IEnumerable
    dataSource)
               at System.Web.UI.WebControls.ListControl.OnDataBinding(EventArgs e)
               at System.Web.UI.WebControls.ListControl.PerformSelect()
               at System.Web.UI.WebControls.BaseDataBoundControl.DataBind()
               at System.Web.UI.Control.DataBindChildren()
               at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding)
               at System.Web.UI.Control.DataBind()
               at System.Web.UI.Control.DataBindChildren()
               at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding)
               at System.Web.UI.Control.DataBind()
               at System.Web.UI.Control.DataBindChildren()
               at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding)
               at System.Web.UI.Control.DataBind()
               at System.Web.UI.Control.DataBindChildren()
               at System.Web.UI.Control.DataBind(Boolean raiseOnDataBinding)
               at System.Web.UI.WebControls.DetailsView.CreateChildControls(IEnumerable
    dataSource, Boolean dataBinding)
               at System.Web.UI.WebControls.CompositeDataBoundControl.PerformDataBinding(IEnumerable
    data)
               at System.Web.UI.WebControls.DetailsView.PerformDataBinding(IEnumerable
    data)
               at System.Web.UI.WebControls.DataBoundControl.OnDataSourceViewSelectCallback(IEnumerable
    data)
               at System.Web.UI.DataSourceView.Select(DataSourceSelectArguments
    arguments, DataSourceViewSelectCallback callback)
               at System.Web.UI.WebControls.DataBoundControl.PerformSelect()
               at System.Web.UI.WebControls.BaseDataBoundControl.DataBind()
               at System.Web.UI.WebControls.DetailsView.DataBind()
               at storeUpdate.GvStoresSelect_SelectedIndexChanged(Object sender, EventArgs e) in line 233
               at System.EventHandler.Invoke(Object sender, EventArgs e)
               at System.Web.UI.WebControls.GridView.OnSelectedIndexChanged(EventArgs e)
               at System.Web.UI.WebControls.GridView.HandleSelect(Int32 rowIndex)
               at System.Web.UI.WebControls.GridView.HandleEvent(EventArgs e, Boolean causesValidation, String validationGroup)
               at System.Web.UI.WebControls.GridView.OnBubbleEvent(Object source, EventArgs e)
               at System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args)
               at System.Web.UI.WebControls.GridViewRow.OnBubbleEvent(Object source,
    EventArgs e)
               at System.Web.UI.Control.RaiseBubbleEvent(Object source, EventArgs args)
               at System.Web.UI.WebControls.LinkButton.OnCommand(CommandEventArgs e)
               at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String
    eventArgument)
               at System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String
    eventArgument)
               at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler
    sourceControl, String eventArgument)
               at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData)
               at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
          InnerException:</p>
  </blockquote>