Javascript - JSON.parse: unexpected end of data - Error when using valid JSON. What am I doing wrong?

So, I've found similar questions about JQuery in which you do not need to parse. Since I am using the AJAX XMLHttpRequest, from what I understand, the parse is necessary. The error is given on the line:

text = JSON.parse(jsonGet.responseText);

Error:

JSON.parse: unexpected end of data  
text = JSON.parse(jsonGet.responseText);

Relevant parts of the function:

function populateList(){
//retrieves list from the server, adds it to the option box
    if(toggle == 0){
        var jsonGet = new XMLHttpRequest();
        jsonGet.open("GET","./json/GetAllEvents.php",true);
        jsonGet.onreadystatechange = function () {
                text = JSON.parse(jsonGet.responseText);   //ERROR HERE
                //updating html with data received
        };
        jsonGet.send();
        toggle = 1;
    } else {}

};

The JSON returned looks like this (without the line breaks):

{"success":true,
"number_of_rows":2,
"data":[
    {"id":"7","event_name":null,"day":3,"start_time":510,"end_time":617},
    {"id":"8","event_name":null,"day":1,"start_time":510,"end_time":617}
]}

JSONLint says that the above is valid. I guess I will take a look into whether XMLHttpRequest does anything strange. Firefox continues to function (even though firebug shows the error), IE9 stops at this point though.

I'm pretty stumped. Any help is appreciated.