java调用ExecuteBillQuery接口报错

{
\"FieldKeys\": \"FID,
FBillNo,
FDate,
FMaterialId,
FMaterialId.FName,
FQty\",
\"FilterString\": \"\",
\"OrderString\": \"FBillNo\",
\"StartRow\": 0,
\"Limit\": 50,
\"TopRowCount\": 2000
}
不知道是不是json格式问题。。

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: A. 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: A. 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=5.1.371.4, 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}