Show Alertbox

Question

protected void btnConnect_Click(object sender, EventArgs e)
 {
try
{
dbquery.getconnection(txtsname.Text, txtuname.Text, txtpwd.Text);

 pnlDB.Visible = true;
pnlCN.Visible = true; ddlDB();

}
catch (Exception ex)


{
 lblex.Visible = true; string p = ex.Message.ToString();
Response.Write("<script language='javascript'>alert(" + p + ")</script>");
 lblex.Text = p;
 pnlDB.Visible = false; pnlCN.Visible = true; }

}

I tried to connect server ..its not correct info it want to show error msg in alert box serverside


How to show the catch error in alertbox in server side