THIS:
this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);
this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;
this->ClientSize = System::Drawing::Size(471, 262);
this->Controls->Add(this->comboBox2);
this->Controls->Add(this->label2);
this->Controls->Add(this->comboBox1);
this->Controls->Add(this->label1);
this->Controls->Add(this->label3);
this->Controls->Add(this->progressBar1);
this->Controls->Add(this->textBox1);
this->Controls->Add(this->button2);
this->Controls->Add(this->button1);
this->Name = L"Form1";
this->Text = L"Form1";
this->ResumeLayout(false);
this->PerformLayout();
IS NOT THE SAME AS:
this->components = (gcnew System::ComponentModel::Container());
this->serialPort1 = (gcnew System::IO::Ports::SerialPort(this->components));
this->comboBox1 = (gcnew System::Windows::Forms::ComboBox());
this->label1 = (gcnew System::Windows::Forms::Label());
this->label2 = (gcnew System::Windows::Forms::Label());
this->comboBox2 = (gcnew System::Windows::Forms::ComboBox());
this->button1 = (gcnew System::Windows::Forms::Button());
this->button2 = (gcnew System::Windows::Forms::Button());
this->textBox1 = (gcnew System::Windows::Forms::TextBox());
this->progressBar1 = (gcnew System::Windows::Forms::ProgressBar());
this->label3 = (gcnew System::Windows::Forms::Label());
this->SuspendLayout();
It seems that you forgot to add:
this->Controls->Add(this->serialPort1);
So IMHO, you pasted just enough code to determine the error.