Saludos, ¿que hago mal en el getJSON?

[ekos77]

$("#botonData").on("click", function(){
var NewData ="";
$.getJSON("FIle.json", function(result){
$.each(result, function(i, field){
NewData += "{ year: "+field.Data+", value: "+field.IM+"},";
});
morris1.setData(NewData); //Fail
//console.log(NewData); Ok
});
});