I have made a custom datatype using the umbraco.editorControls.userControlGrapper.IUsercontrolDataEditor. The control is a calendar controll, but when a save a node, the day and month is swapping. This is not happening when I publish.

Why is this happening?

    public partial class RDateTime : System.Web.UI.UserControl, umbraco.editorControls.userControlGrapper.IUsercontrolDataEditor
    {
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        public object value
        {
            get
            {
                return Dato.SelectedDate;
            }
            set
            {
oldValue.Text = value.ToString();
            }
        }
    }
}

This is a simplyfied version of the sourcecode.

Umbraco version 4.0.3