He is not referring to the checkbox inside the RadGrid's Column's tag.
He is referring to a checkbox he is trying to place in the FormTemplate tag.
I am having the same trouble.
The GridCheckBoxColumn works greate to render a checkbox inside the grid, but when you clic "Add new record" an error is thrown, indicating that the value null is not a valid value for the checkbox "checked" property.
I have tried Bind, Eval, and it won't work.
Here is my code:
|<asp:CheckBox ID="Activada" runat="server" Checked='<%# Bind("Activada") %>' />
I hope you can help us, I haven't seen a solution to this in any post, or any examples from you, and it is a very basic and common situation.
Thanks in advance.