Please read and correct this code

If i have two buttons event handlers  how to determined in a calendar selectionchange event handler that which button press first than other.i.e "I want to select date from one calendar with two buttons for two textboxes i.e startdate & enddate" 

ublic partial class Default6 : System.Web.UI.Page

protected void Page_Load(object sender, EventArgs e)

protected void Cal1_SelectionChanged(object sender, EventArgs e)

if (btnstart.Enabled.Equals(true))

Cal1.Visible = false;

btnstart.Enabled = false;

btnend.Enabled = true;

else

if (btnend.Enabled.Equals(true))

Cal1.Visible = false;

btnend.Enabled = false;

btnstart.Enabled = true;

protected void txtstart_TextChanged(object sender, EventArgs e)

protected void btnstart_Click(object sender, EventArgs e)

Cal1.Visible = true;

// txtstart.Text = Cal1.SelectedDate.ToShortDateString();

// Cal1.Visible = false;

protected void txtend_TextChanged(object sender, EventArgs e)

protected void btnend_Click(object sender, EventArgs e)

Cal1.Visible = true;

// txtend.Text = Cal1.SelectedDate.ToShortDateString();

// Cal1.Visible = false;