getting error Internal server error when calling gateway service

hi,

  I am getting error Internal server error  when I  calling customer_creating_entity method from gateway and i am getting data from get method.

I write following ajax code in sapui5.

jQuery.ajax({

                     beforeSend: function(xhrObj){

                             xhrObj.setRequestHeader("X-Requested-With","XMLHttpRequest");

                             xhrObj.setRequestHeader("Content-Type","application/json");

                             xhrObj.setRequestHeader("Accept","application/json");

                     },

                     type: "POST",

                     contentType: "application/json",

                     url: url,

                     dataType: "json",

                     data: {

                  "CoID": 20241,

                     "CoName": "krishna",

                              "ContactNo": "12345678990"

                    },

                 success: function(xml) {

                   //oModel.setData(data);            

                   alert("success to post");

                 },

                 error: function(xml) {

                   //oModel.setData(data);       

                   alert("fail to  post");

                   alert(xml);

                 }

             });