[C# Windows Forms] Open form in static main

Question

Hi everybody.
I have 2 form : MainFrm is main form and Notification is form used to show notification.
In program.cs :

static void Main()
{
bool result;
Mutex mutex = new Mutex(true, "UniqueAppId", out result);

if (!result)
{
//MainFrm.showNotification("KyAppAPI??????????");

//MessageBox.Show("KyAppAPI??????????");

Notification notiBox = new Notification();
notiBox.Show();
return;
}

Application.EnableVisualStyles();

Application.SetCompatibleTextRenderingDefault(false);

Application.Run(new MainFrm());

GC.KeepAlive(mutex);

}

[/CODE]

I use mutex to keep application run once. If application already running, form Notification will show.
But my code work not right, form Notification not shown.
In MainFrm, I has a static method showNotification (using Tulpep Notification). I try calling this method in static main, but it not working, too.
However, if I use MessageBox, it working fine.
I don't know where the problem is. Please help me.