Dynamically created CheckBoxs event fires on second click not first

I have created CheckBoxs dynamically in GridView but the CheckedChanged event fires when I click the twice.

Where I'am wrong?

protected void GridView1_RowCreated(object sender, GridViewRowEventArgs e)
{
    // check if it's not a header and footer
    if (e.Row.RowType == DataControlRowType.Row)
    {
        CheckBox chk = new CheckBox();

        chk.AutoPostBack = true;

        // add checked changed event to checkboxes
        chk.CheckedChanged += new EventHandler(chk_CheckedChanged);

        e.Row.Cells[1].Controls.Add(chk); // add checkbox to second column
    }
}