String was not recognized as a valid DateTime.?

dd-MM-yyyy

ID	int	Unchecked
Party1	nvarchar(50)	Checked
Party1ADD	nvarchar(50)	Checked
Party2	nvarchar(50)	Checked
Party2add	nvarchar(50)
Capacity	nvarchar(50)	
Agper	nvarchar(50)	
AGtop	nvarchar(50)	
AGplace	nvarchar(50)	
Tnco	nvarchar(50)	
Status	nvarchar(50)	
Endno	nvarchar(50)	
Mulahiq	varchar(50)	
Qarar	nvarchar(50)	
entered	nvarchar(MAX)	
username	nvarchar(MAX)	
[update]	nvarchar(MAX)	
[last update date]	datetime2(0)	
laspusername	nvarchar(MAX)	
[entered-date]	datetime2(0)	
AGend	datetime	
AGdt	datetime	
Enddt	datetime	

 protected void Button2_Click(object sender, EventArgs e)
    {
        string dt = DateTime.Now.ToShortDateString();
        
        try
        {

            DAL.InsertAgreement3(TextBox1.Text, TextBox2.Text,TextBox3.Text,TextBox4.Text,TextBox5.Text,TextBox6.Text,TextBox7.Text,TextBox8.Text,TextBox9.Text,TextBox10.Text,TextBox12.Text,TextBox11.Text,TextBox13.Text,TextBox14.Text,TextBox15.Text,TextBox16.Text, Session["username"].ToString());
            info.Style.Add("display", "block");
            lblerror.Visible = true;
            lblerror.Text = "Successfuly Inserted Record...";

            Response.Redirect("Agreement3.aspx");
            //clearTxt();
            
        }
        catch (Exception ex)
        {
            info.Style.Add("display", "block");
            lblerror.Visible = true;
            lblerror.Text = "Error Occured while adding.....!!!!! " + " " + ex.Message;

        }
}



//DAL 

<pre>

 public static void InsertAgreement3(string Agdt, string party1, string partyadd, string party2, string party2add, string capacity, string agper, string agtop, string agplace, string Termscon, string Agend, string Status, string EndNo, string Enddate, string Mulahiq, string Qarar, string uname)
    {
        DateTime dt;
        string sdt = System.DateTime.Now.ToString();
        string sdt1 = DateTime.Now.ToShortDateString();

        SqlConnection sqlconn = new SqlConnection(ConnString);
        try
        {
            sqlconn.Open();
            string Query = "INSERT INTO [tbl_agreement1]([AGdt],[Party1],[Party1ADD],[Party2],[Party2ADD],[Capacity],[AGper],[AGtop],[AGPlace],[Tnco],[AGend],[Status],[Endno],[Enddt],[Mulahiq],[Qarar],[entered],[entered-date],[username]) VALUES (N'" + DateTime.Parse(Agdt).ToString(new CultureInfo("en-US")) + "',N'" + party1 + "',N'" + partyadd + "',N'" + party2 + "',N'" + party2add + "',N'" + capacity + "',N'" + agper + "',N'" + agtop + "',N'" + agplace + "',N'" + Termscon + "',N'" + DateTime.Parse(Agend).ToString(new CultureInfo("en-US")) + "',N'" + Status + "',N'" + EndNo + "',N'" + DateTime.Parse(Enddate).ToString(new CultureInfo("en-US")) + "',N'" + Mulahiq + "',N'" + Qarar + "',N'" + "New Record Added" + "',N'" + DateTime.Parse(sdt).ToString(new CultureInfo("en-US")) + "',N'" + uname + "' )";
            SqlCommand sqlcomm = new SqlCommand(Query, sqlconn);
            sqlcomm.ExecuteNonQuery();
        }
        catch (Exception ex)//getting error here
        {

        }
        finally
        {
            sqlconn.Close();
        }