Form.Hide() and Form.Visable = false; Don't Work

[ziycon]

This function is in a class file, can't get the frmLogin form to hide when a user logins in, the frmMain will open fine though!???

public void login(string username,string password)
       {
           DBConnect(); //Internal DB connection call

           frmLogin login = new frmLogin();

           md5 = new MD5CryptoServiceProvider();
           originalBytes = ASCIIEncoding.Default.GetBytes(password);
           encodedBytes = md5.ComputeHash(originalBytes);

           QueryString = "SELECT username,password FROM userdat WHERE username='" + username + "'";
           command.CommandText = QueryString;
           try
           {
               Reader = command.ExecuteReader();
               Reader.Read();
               try
               {
                   if (Reader.GetValue(0).ToString() != null)
                   {
                       if ((username == Reader.GetValue(0).ToString()) && (BitConverter.ToString(encodedBytes) == Reader.GetValue(1).ToString()))
                       {
                           login.Hide();
                           new frmMain().Show();
                       }
                       else
                       {
                           MessageBox.Show("Username or password are incorrect.", "Simplicity", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                       }
                   }
               }
               catch(MySqlException)
               {
                   MessageBox.Show("Username is incorrect.", "Simplicity", MessageBoxButtons.OK, MessageBoxIcon.Warning);
               }
                
		   }
           catch (MySqlException ex01)
           {
               MessageBox.Show("Error communicating with the database.\nInternal Error Code: x00001\nError Code: "+ex01, "Simplicity", MessageBoxButtons.OK, MessageBoxIcon.Error);
           }

           DBDisconnect(); //Internal DB close connection call.
       }

[Plater]

You are not hiding your existing login form, you are creating a new one and hiding THAT one.
You will need to hide the instance of the one already opened.

[ziycon]

I've added the function to return a boolean value to the login form so if the login details are all correct it'll return a true value so on the login form i have the below if statement and it seems to be working ok, thanks for that Plater.

validate = dbconn.login(txtUsername.Text, txtPassword.Text);
if (validate)
   this.Hide();