private void txtREf_Validating(object sender, CancelEventArgs e)
{
if (FAQ.DrPOExist(txtREf.Text))
{
e.Cancel = true;
txtREf.Focus();
errorProvider1.SetError(txtREf, "PO No is Exist");
}
else
{
e.Cancel = false;
errorProvider1.SetError(txtREf, null);
}
}
