I'm trying to detect whether or not the user have save their work before closing the program. I've tried the below coding:

```
void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    if (e.CloseReason == CloseReason.UserClosing)
        MessageBox.Show("Unsave Work");
}

```

But it does not work. Nothing happen when I close the program.