store data of DATE datatype in sql from front end i.e asp form

This Way:

<form id="form1" runat="server">
    <div>
        Enter Date
        <br />
        <asp:TextBox ID="txtDOB" runat="server" />
        <asp:Calendar ID="Calendar1" runat="server" OnSelectionChanged="Calendar_OnSelectionChanged">
        </asp:Calendar>
        <asp:Button ID="btn" runat="server" Text="Save" OnClick="Save" />
    </div>
    </form>

C#:

protected void Calendar_OnSelectionChanged(object sender, EventArgs e)
    {
        this.txtDOB.Text = this.Calendar1.SelectedDate.ToString();
    }

    protected void Save(object sender, EventArgs e)
    {
        string constr = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
        string sqlStatment = "INSERT INTO DateOfBirth VALUES(@DOB)";
        using (SqlConnection con = new SqlConnection(constr))
        {
            using (SqlCommand cmd = new SqlCommand(sqlStatment, con))
            {
                con.Open();
                cmd.Parameters.AddWithValue("@DOB", Convert.ToDateTime(this.txtDOB.Text));
                cmd.ExecuteNonQuery();
                con.Close();
            }
        }
    }

SQL Table:

CREATE TABLE [dbo].[DateOfBirth](
	[Id] [int] IDENTITY(1,1) NOT NULL,
	[DoB] [datetime] NOT NULL,
 CONSTRAINT [PK_DateOfBirth] PRIMARY KEY CLUSTERED 
(
	[Id] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

I have added asp Calendar control also. If you type Date as dd/MM/yyyy then it will give your error like String was not recognized as a valid DateTime. but it will allow you for these date format MM/dd/yyyy and yyyy/MM/dd.

Thank You.