Can't call the action with the json,please help,thanks!

i want't get the data from server instead of local,so i set the datatype to “json”,the url to the action on the server ““,the action is confirm correct,there is test on browser,also i change the action url

“http://localhost:8080/eapsoft/car/jqGrid_getJsonData.action”,open in the browser it's correct and return data,but with the jqGrid url ,it's invalid,not call!

please help,what's the problem? thanks all!

here is the code: