Issue with CallFunction of V2 Model

Hi

I have an issue with the call function of V2 Model. While calling the function import, the console errors out saying

"uncaught (promise)   undefined
(anonymous function @ODataModel.js

My function call is as below

var entry = {
  'CountBack':'X',
  'CountBack_Lvl':'X',
  'CountBack_SLvl':' ',
  'Def_No_Of_Hu':'2'  
  };
oModel.callFunction("/DemoEWM","GET",entry,null,function(oData,oResponse){
  alert("success:"+oResponse);
  },function(oError){
  alert("error"+oError); 
  });

I tried with POST too, but same results.

What is missing here. I am using 1.34 version of UI5

Thanks

Sandip