solve error...Failed to convert parameter value from a ListItem to a String.

See more:

C#

i want date value insert into table using three dropdownlist but error show

error:-Failed to convert parameter value from a ListItem to a String.

code following:-

protected void Button2_Click(object sender, EventArgs e)
{
string image = FileUpload1.FileName;

string ext = image.Substring(image.LastIndexOf("."));

if (ext.ToLower() == ".jpg" || ext.ToLower() == ".jpeg" || ext.ToLower() == ".gif")
{
FileUpload1.SaveAs(MapPath("images\\") + image);

path1 = @"images/" + image;
}


string date = DropDownList1.SelectedValue.ToString() + "-" + DropDownList2.SelectedValue.ToString() + "-" + DropDownList3.SelectedValue.ToString();


con.Open();

SqlCommand cmd = new SqlCommand("instud", con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Connection = con;
cmd.Parameters.Add("@date", SqlDbType.VarChar, 50).Value = TextBox1.Text;
cmd.Parameters.Add("@name", SqlDbType.VarChar, 50).Value = TextBox2.Text;
cmd.Parameters.Add("@gendr", SqlDbType.VarChar, 50).Value = RadioButtonList1.SelectedItem;
ERROR:- cmd.Parameters.Add("@dob", SqlDbType.VarChar, 50).Value =date;
cmd.Parameters.Add("@fnam", SqlDbType.VarChar, 50).Value = TextBox5.Text;
cmd.Parameters.Add("@focc", SqlDbType.VarChar, 50).Value = TextBox6.Text;
cmd.Parameters.Add("@pradd", SqlDbType.VarChar, 100).Value = TextBox7.Text;
cmd.Parameters.Add("@padd", SqlDbType.VarChar, 100).Value = TextBox8.Text;
cmd.Parameters.Add("@mob", SqlDbType.VarChar, 50).Value = TextBox9.Text;
cmd.Parameters.Add("@cid", SqlDbType.Int).Value = TextBox10.Text;
cmd.Parameters.Add("@cnam", SqlDbType.VarChar, 50).Value = TextBox11.Text;
cmd.Parameters.Add("@duration", SqlDbType.VarChar, 50).Value = TextBox12.Text;
cmd.Parameters.Add("@catgy", SqlDbType.VarChar, 50).Value = TextBox13.Text;
cmd.Parameters.Add("@img", SqlDbType.VarChar, 50).Value = path1;
cmd.ExecuteNonQuery();
cmd.Dispose();
con.Close();
clear();
Label15.Visible = true;
Label15.Text = "Insert Record Successfully";

}