DataGridViewCheckBox CheckedChange Event

I added Checkboxcolumn near my columns. i googling a lot but i cant find a good answer.

I Want to make Btn_Edit.Visiable=false; if checkbox checked count is up to 1. after my researches i go to Use CellContentClick event but it isn't work fine.

My Code:

private void GrdVw_Reception_CellContentClick_1(object sender, DataGridViewCellEventArgs e)
    {
        if (GrdVw_Reception.CurrentCellAddress.X == 0)
        {
            int UpTpOne = 0;
            bool flag = false;

            for (int i = 0; i < GrdVw_Reception.Rows.Count; i++)
            {

                if (Convert.ToBoolean(GrdVw_Reception.Rows[i].Cells["checkColumn"].Value) == true)
                {
                    UpTpOne = UpTpOne + 1;

                    if (UpTpOne == 1)
                    {
                        flag = true;
                    }
                    else
                    {
                        flag = false;
                    }
                }
            }

            if (flag == true)
            {
                Btn_Edit.Visible = true;
            }
            else
            {
                Btn_Edit.Visible = false;
            }
        }
    }

In this step when i run the program and click on checkboxes for first Btn_Edit dont go to true and for secound click Btn_Edit.Visiable go to true.

I want checkedchange event or an event that when i click on checkbox go to event codes in that moment.

(Sorry for bad English)