Hotkey not working when showintaskbar set is false

using HotKey;
    public partial class MainForm : Form
    {
    	private Hotkeys.GlobalHotkey ghk;
    	public MainForm()
    	{
    		InitializeComponent();
    		ghk = new Hotkeys.GlobalHotkey(Constants.ALT + Constants.SHIFT, Keys.M, this);
    	}

    	private void HandleHotkey()
    	{
    		WriteLine("Hotkey pressed!");
    	}
    	protected override void WndProc(ref Message m)
    	{
    		base.WndProc(ref m);

    		switch (m.Msg)
    		{
    			case Constants.WM_HOTKEY_MSG_ID:
    				// Hotkey was pressed
    				HandleHotkey();
    				break;
    		}
    	}

    	private void MainForm_Load(object sender, EventArgs e)
    	{
    		WriteLine("Trying to register SHIFT+ALT+O");
    		if (ghk.Register())
    		{
    			this.WindowState = FormWindowState.Minimized;
    			this.ShowInTaskbar = false;
    			WriteLine("Hotkey registered.");
    		}
    		else
    		{
    			WriteLine("Hotkey failed to register");
    		}
    	}

    	private void WriteLine(string text)
    	{
    		textBox1.Text += text + Environment.NewLine;
    	}
    }