PHP调用webapi生成销售出库单报错

{

"Creator": "", "NeedUpDateFields": "", "Model": {

"FID": 0, "FBillTypeID": {

"FBILLTYPEID": "ad0779a4685a43a08f08d2e42d7bf3e9" }, "FBillNo": "", "FDate": 1448688878, "FSaleOrgId": {

"FNUMBER": "100" }, "FCustomerID": {

"FNUMBER": "LSKH" }, "FCarrierID": {

"FSupplierId": 1, "FNUMBER": "VEN00001", "FNAME": "" }, "FEntity": {

"first": {

"FMaterialID": {

"FNumber": "CMKCHLB01_SYS0002" }, "FUnitID": {

"FNumber": "001" }, "FMaterialName": "钢笔", "FStockID": {

"FNumber": "001" }, "FStockStatusID": {

"FNumber": "KCZT01_SYS" }, "FRealQty": "2", "FEntrynote": "平台购买" } }, "FCorrespondOrgId": {

"FOrgID": 2, "FNUMBER": "100", "FNAME": "" }, "FCarriageNO": "", "FSalesGroupID": {

"FEntryId": 0, "FNUMBER": "100", "FNAME": "" }, "FStockOrgId": {

"FOrgID": 2, "FNUMBER": "100", "FNAME": "" }, "FDeliveryDeptID": {

"FDEPTID": 1, "FNUMBER": "BM000001", "FNAME": "" }, "FNote": "22222", "FCreateDate": 1448688878, "FApproveDate": 1448688878, "FCancelDate": 1448688878 }}

老师 我现在正在调用webapi接口生成销售出库单，转换后的json 如上（有的不需要的数据我没传） ，生成销售出库单“报错未将对象引用设置到对象的实例”是怎么回事啊