diff --git a/Contabilidad/RegPrePolizaS.aspx.vb b/Contabilidad/RegPrePolizaS.aspx.vb
index f93a39a5f..50deab8a5 100644
--- a/Contabilidad/RegPrePolizaS.aspx.vb
+++ b/Contabilidad/RegPrePolizaS.aspx.vb
@@ -1811,7 +1811,7 @@ Partial Class ContabilidadC_RegPrePolizaS
                 dr("CvePersonal") = DdlPersonalE.SelectedValue.ToEntero
                 dr("CveCliente") = DdlClientesE.SelectedValue.ToEntero
                 dr("CveVenta") = DdlVentasE.SelectedValue.ToEntero
-                dr("FolioFactura") = If(DdlComprasE.Visible = True, DdlComprasE.SelectedItem.ToString, If(DdlVentasE.Visible = True, DdlVentasE.SelectedItem.ToString, ""))
+                dr("FolioFactura") = If(DdlComprasE.Visible = True AndAlso DdlComprasE.SelectedItem IsNot Nothing, DdlComprasE.SelectedItem.ToString, If(DdlVentasE.Visible = True AndAlso DdlVentasE.SelectedItem IsNot Nothing, DdlVentasE.SelectedItem.ToString, ""))
                 dr("Modificado") = True
 
                 dr("ContadoCuenta") = DdlModalConceptoCuenta.SelectedValue.ToEntero