求指导求救。。JAVA调用K3Cloud WebAPI接口问题

问题描述：
java系统通过http的形式调用出差单的ExecuteBillQuery接口报错，其他类似查看（view），保存（save）已同样的方式调用可正常调用

这是参数传入的json串：
{\"FormId\":\"ER_ExpenseRequest_Travel\",
\"FieldKeys\":\"FTravelStartSite,FTravelEndSite,FBillNo,FTravelStartDate,FTravelEndDate,F_PAEZ_days,FReason,FStaffID\",
\"FilterString\":\"FTravelStartDate>'2016-04-02 00:00:00'\",
\"OrderString\":\"\",
\"TopRowCount\":\"0\",
\"StartRow\":\"0\",
\"Limit\":\"10\"}
在web API中测试可以正常返回值，但在java代码中作为参数调用ExecuteBillQuery接口时即报错
报错信息：
response_error:{"InnerExWrapper":{"IsEmpty":false,"Data":{},"HelpLink":null,"Message":"调用的目标发生了异常。","Source":null,"StackTrace":" 在 System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)\r\n 在 System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)\r\n 在 System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)\r\n 在 Kingdee.BOS.ServiceFacade.KDServiceFx.ServiceExecutor.Execute(KDServiceContext context, ServiceType svcType, String[] paraValues, SerializerProxy serializeProxy, ServiceType beginMethod)","TargetSite":null,"ExceptionType":"System.Reflection.TargetInvocationException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089","InnerException":{"IsEmpty":false,"Data":{},"HelpLink":null,"Message":"Unexpected character encountered while parsing value: E. Line 1, position 1.","Source":null,"StackTrace":" 在 Kingdee.BOS.WebApi.FormService.QueryBillService.ExecuteBillQuery(String data)\r\n 在 Kingdee.BOS.WebApi.ServicesStub.DynamicFormService.ExecuteBillQuery(String data)","TargetSite":null,"ExceptionType":"Newtonsoft.Json.JsonReaderException, Newtonsoft.Json, Version=4.0.0.0, Culture=neutral, PublicKeyToken=null","InnerException":null}},"ClassName":"Kingdee.BOS.ServiceFacade.ServiceException","Message":"Unexpected character encountered while parsing value: E. Line 1, position 1.","Data":null,"InnerException":null,"HelpURL":null,"StackTraceString":" 在 Kingdee.BOS.ServiceFacade.KDServiceFx.ServiceExecutor.Execute(KDServiceContext context, ServiceType svcType, String[] paraValues, SerializerProxy serializeProxy, ServiceType beginMethod)\r\n 在 Kingdee.BOS.ServiceFacade.KDServiceFx.ExecuteServiceModule.OnProcess(KDServiceContext context)\r\n 在 Kingdee.BOS.ServiceFacade.KDServiceFx.ModulePipeline.ExcuteRequest(KDServiceContext context)\r\n 在 Kingdee.BOS.ServiceFacade.KDServiceFx.RequestExcuteRuntime.BeginRquest(RequestExtractor requestExtractor, WebContext webCtx)\r\n 在 Kingdee.BOS.ServiceFacade.KDServiceFx.RequestExcuteRuntime.StartRequest(RequestExtractor requestExtractor, WebContext context)\r\n 在 Kingdee.BOS.ServiceFacade.KDServiceFx.KDSVCHandler.ExecuteRequest(WebContext ctx, RequestExtractor requestExtractor)\r\n 在 Kingdee.BOS.ServiceFacade.KDServiceFx.KDSVCHandler.ProcessRequestInternal(WebContext webCtx, RequestExtractor requestExtractor)","RemoteStackTraceString":null,"RemoteStackIndex":0,"ExceptionMethod":"8\nExecute\nKingdee.BOS.ServiceFacade.KDServiceFx, Version=6.0.413.1, Culture=neutral, PublicKeyToken=null\nKingdee.BOS.ServiceFacade.KDServiceFx.ServiceExecutor\nSystem.String Execute(Kingdee.BOS.ServiceFacade.KDServiceFx.KDServiceContext, Kingdee.BOS.ServiceFacade.KDServiceFx.ServiceType, System.String[], Kingdee.BOS.ServiceFacade.SerializerProxy, Kingdee.BOS.ServiceFacade.KDServiceFx.ServiceType)","HResult":-2147467259,"Source":"Kingdee.BOS.ServiceFacade.KDServiceFx","WatsonBuckets":null,"_httpCode":500}

具体的调用方式在附件里，跪求这是什么原因啊。。卡好几天了。。。