使用WebApi导入生产订单出现错误Object must implement IConvertible.

这是我的json：
{
"Creator": "jj",
"NeedUpDateFields": [],
"Model": {
"FID": 0,
"FBILLNO": "",
"FPPBOMType": {
"FNumber": "直接入库-普通生产"
},
"FDate": "2017-01-22",
"FPrdOrgId": {
"FNumber": "101.2"
},
"FOwnerTypeId": {
"FNumber": "101.2"
},
"FTreeEntity": [
{
"FProductType": "主产品",
"FMaterialId": {
"FNumber": "CH4444"
},
"FUnitID": {
"FNumber": "Pcs"
},
"FQty": 10,
"FPlanStartDate": "2017-01-23",
"FPlanFinishDate": "2017-01-23",
"FStockInOrgId": {
"FNumber": "101.2"
},
"FReqType": "相关",
"FCreateType": "手工录入"
}
]
}
}
这是错误信息：
{"Result":{"ResponseStatus":{"ErrorCode":500,"IsSuccess":false,"Errors":[{"FieldName":"Object must implement IConvertible.","Message":" at System.Convert.ChangeType(Object value, Type conversionType, IFormatProvider provider)\r\n at Kingdee.BOS.Orm.Metadata.DataEntity.DefaultGetSetValue.SetValue(DynamicObject obj, DynamicProperty property, Object oldValue, Object& newValue)\r\n at Kingdee.BOS.Orm.Metadata.DataEntity.DynamicProperty.SetValuePrivate(DynamicObject dataEntity, Object newValue)\r\n at Kingdee.BOS.Core.Metadata.FieldElement.ItemClassTypeField.SetFieldValue(IDynamicFormModel model, DynamicObject activeRow, Object value)\r\n at Kingdee.BOS.Core.DynamicForm.AbstractDynamicFormModel.UpdateFieldValue(Field field, DynamicObject obj, Object value, Int32 row)\r\n at Kingdee.BOS.Core.DynamicForm.AbstractDynamicFormModel.UpdateField(Field field, DynamicObject activeRow, Object value, Int32 rowIndex, Object oldValue)\r\n at Kingdee.BOS.Core.DynamicForm.AbstractDynamicFormModel.SetValue(Field field, DynamicObject activeRow, Object value, Int32 rowIndex)\r\n at Kingdee.BOS.WebApi.FormService.MapPropertyService.SetSimpleProperty(Field field, DynamicObject target, Object value, Int32 rowIndex)\r\n at Kingdee.BOS.WebApi.FormService.MapPropertyService.MapComplexProperty(String pkProperty, Dictionary`2 sourceObj, DynamicObject targetObj, Int32 rowIndex, HashSet`1 NeedUpDateFields)\r\n at Kingdee.BOS.WebApi.FormService.Save.Revole()\r\n at Kingdee.BOS.WebApi.FormService.Save.Execute()\r\n at Kingdee.BOS.WebApi.FormService.BillOperationService.ExecuteOperation(FormOperation op, String data)","DIndex":0}],"SuccessEntitys":[],"SuccessMessages":[]}}}
请各位老师帮忙解决一下问题，谢谢