调用淘宝api问题，获取数据response那一行报错

TaobaoClient client = new DefaultTaobaoClient(su.getUrl(), su.getAppKey(), su.getAppSercet());
WangwangEserviceGroupmemberGetRequest req = new WangwangEserviceGroupmemberGetRequest ();
if(managerId!=null && !"".equals(managerId)){
req.setManagerId("cntaobao"+managerId);
}
try {
WangwangEserviceGroupmemberGetResponse response = client.execute(req , su.getSessionKey());//这一行报错，获取不到数据

        错误信息：
        java.lang.IllegalArgumentException: expected value at column 1

        at com.taobao.api.internal.util.json.ExceptionErrorListener.error(ExceptionErrorListener.java:7)
at com.taobao.api.internal.util.json.JSONValidator.error(JSONValidator.java:211)
at com.taobao.api.internal.util.json.JSONValidator.valid(JSONValidator.java:33)
at com.taobao.api.internal.util.json.JSONValidator.validate(JSONValidator.java:20)

看起来貌似是参数不对IllegalArgumentException不合法的参数异常。，你看下ExceptionErrorListener.java:7 这一行是什么，大概逻辑

IllegalArgumentException不合法的参数异常