第三方调用接口保存凭证问题

var sFormID = "GL_VOUCHER";
var sContent = "{\"Creator\":\"String\",\"NeedUpDateFields\":[],\"Model\":{\"FVOUCHERID\":0,\"FAccountBookID\":{\"FNumber\":\"001\"},\"FDate\":\"2016-08-09\",\"FSystemID\":{\"FNumber\":\"gl\"},\"FVOUCHERGROUPID\":{\"FNumber\":\"PRE001\"},\"GL_VOUCHER__FEntity\":[{\"FEXPLANATION\":\"按内码aa\",\"FACCOUNTID\":{\"FNumber\":\"1001.01\"},\"FDEBIT\":\"100\"},{\"FEXPLANATION\":\"2aa\",\"FACCOUNTID\":{\"FNumber\":\"1002.01\"},\"FCREDIT\":\"100\"}]}}";
object[] voucher = new object[]
{
sFormID,
sContent
};
ret = clt.Execute("Kingdee.BOS.WebApi.ServicesStub.DynamicFormService.Save", voucher);

报错：

Result":{"ResponseStatus":{"ErrorCode":500,"IsSuccess":false,"Errors":[{"FieldName":"AbstractInteractionResult","Message":"AbstractInteractionResult.InteractionContext is null"}]},"Id":""}}
是什么意思？
另，能否说明一下每个字段的含义以及取值，谢谢。