Dropdown list databinding error

[primagic]

I have a dropdown list within a template field in details view

<asp:TemplateField HeaderText="Allocate Babysitter">
                             <EditItemTemplate>
                             <asp:DropDownList ID="ddlBabysitter" runat="server" SelectedValue='<%# Bind("BabysitterID") %>'  
                                DataSourceID="GetBabysittersList" DataTextField="BabysitterName" 
                                DataValueField="BabysitterID" ondatabinding="PreventErrorOnbinding" >
                                <asp:ListItem Text="none" Value=""></asp:ListItem>
                            </asp:DropDownList>    
                             </EditItemTemplate>
                             <ItemTemplate>
                             <asp:Label ID="lblBabysitter" runat="server" Text='<%# Bind("BabysitterName")%>'></asp:Label>
                             </ItemTemplate>
                             </asp:TemplateField>

I am getting the following error whenever the page loads:

ddlBabysitter' has a SelectedValue which is invalid because it does not exist in the list of items.
Parameter name: value

I read on a website to add the following code to my codebehind which would eliminate the error

 Protected Sub PreventErrorOnbinding(sender As Object, e As EventArgs)
        Dim ddlBabysitter As DropDownList = DirectCast(sender, DropDownList)
        ddlBabysitter.DataBinding -= New EventHandler(AddressOf PreventErrorOnbinding)
        ddlBabysitter.AppendDataBoundItems = True
        Dim li As New ListItem("Make a selection >>", "")
        ddlBabysitter.Items.Insert(0, li)
        Try
            ddlBabysitter.DataBind()
        Catch generatedExceptionName As ArgumentOutOfRangeException
            ddlBabysitter.SelectedValue = ""
        End Try
    End Sub

But now I get the following error:

'Public Event DataBinding(sender As Object, e As System.EventArgs)' is an event, and cannot be called directly. Use a 'RaiseEvent' statement to raise an event.

on the line

ddlBabysitter.DataBinding -= New EventHandler(AddressOf PreventErrorOnbinding)

 

[jbenson001]

First, I've never seen code like that, I can't imagine that would work, and it doesn't based on your error.
Second, stop using the DataSource controls. They are terrible for many reasons, one being that you cannot debug them or any code within them.
Third, you should never have a possible value coming back from the DB that is not present in your DDL. The DDL should contain any possible values.

Lastly, you need to add your event handler like this:
AddHandler ddlBabysitter.DataBinding, AddressOf PreventErrorOnbinding