private void CuitTB_Validated(object sender, EventArgs e)
 {
     if (CuitTB.Text.Trim() == "")
     {
         ProveedorEP.SetError(CuitTB, "Ingrese el CUIT...");
         CuitTB.Focus();
     }
 }
 private void RaSoTB_Validated(object sender, EventArgs e)
 {
     if (RaSoTB.Text.Trim() == "")
     {
         ProveedorEP.SetError(RaSoTB, "Ingrese la Razón social...");
         RaSoTB.Focus();
     }
 }