I created a SQL query and it should update the database after the payment is made, but when I hit the save button, nothing happens, I don’t even get an error.

Save button code:

public override void btnsave_Click(object sender, EventArgs e)
{
     string qry = @" Update tblMain set total=@tot,recevid=@rec,change=@cha,status ='پرداخت شد'  where MainID=@id";

     Hashtable ht = new Hashtable();
     ht.Add("@id", MainID);
     ht.Add("@tot", TextBillAmount.Text);
     ht.Add("@rec", TextRecive.Text);
     ht.Add("@cha", TextChenge.Text);

     if (Mainclass.SQL(qry, ht) > 0)
     {
         guna2MessageDialog1.Buttons = Guna.UI2.WinForms.MessageDialogButtons.OK;
         guna2MessageDialog1.Show("با موفقیت ذخیره شد");
         this.Close();
     }
}

And this is the main class SQL code:

public static int SQL(string qry, Hashtable ht)
{
    int res = 0;

    try
    {
        SqlCommand cmd = new SqlCommand(qry, con);
        cmd.CommandType = CommandType.Text;

        foreach (DictionaryEntry item in ht)
        {
            cmd.Parameters.AddWithValue(item.Key.ToString(), item.Value);
        }

        if (con.State == ConnectionState.Closed) 
        {
            con.Open(); 
        }

        res = cmd.ExecuteNonQuery();

        if (con.State == ConnectionState.Open) 
        {
            con.Close(); 
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.ToString());
        con.Close();
    }

    return res;
}

So far, I have not had such a problem, and if there was a problem, I would at least receive an error message, but this time, nothing happened at all.