Populating Custom Fields On Transactions

We are trying to populate custom fields on transactions via webservices

Testing on a Purchase Order:  The PO gets created successfully, and no errors are returned from webservices, but the fields through the UI do not show the data that was pushed. 

C# Snippet:

po.entity = vendor;              po.customFieldList = new CustomFieldRef[1];              var trxCustomFieldRef = new StringCustomFieldRef();              trxCustomFieldRef.internalId = "custbody12";              trxCustomFieldRef.value = "PO256";              po.customFieldList[0] = trxCustomFieldRef;                              po.orderStatus = PurchaseOrderOrderStatus._pendingReceipt;              po.orderStatusSpecified = true;              po.memo = rsPo.externalComents;              po.location = location;                              if (subsidiary != null)              {                  po.subsidiary = subsidiary;                  _rsLog.log("po.subsidiary" + po.subsidiary);              }                PurchaseOrderItemList list = new PurchaseOrderItemList();              list.item = new PurchaseOrderItem[rsPo.detailLines.Count];              po.itemList = list;                int detailIndex = 0;                foreach (RSOrderDetail rsDetail in rsPo.detailLines)              {                    var references = ItemType.GetRecordRefs(SearchUtilities.GetItemRecord(rsDetail, _service, _rsLog));                  var itemLocationDetail = SearchUtilities.GetLocation(rsDetail, _service, _rsLog);                  _rsLog.log("rsDetail.uom: '" + rsDetail.uom + "'");                  _rsLog.log("rsDetail.purchaseUOM: '" + rsDetail.purchaseUOM + "'");                    var poItem = new PurchaseOrderItem();                  poItem.item = references.ItemRef;                  poItem.quantity