radio button checked change event not working..

Question

  protected void RadioButton1_CheckedChanged(object sender, EventArgs e)

    {

        if (RadioButton1.Checked == true)

        {

            lblSupplier.Visible = true;

            ddlSupplierName.Visible = true;

            lblFinancialYear.Visible = true;

            ddlYear.Visible = true;

            btnSearch.Visible = true;

        }

it's not working..