Strange problems with browser rendering javascript [VS 2010]

I have the following just before my </body>

HTML Code:

---

<script type="text/javascript">
          //success message..
          function OnSuccess(result) {
              if (result) {
                  document.getElementById("<%= lblMessage.ClientID %>").textContent = result;

              }
          }
function CheckForReturnAndComplete() {
              if (event.keyCode === 13) {
                  var txt1 = document.getElementById('<%=text1.ClientID %>').value;
                  var txt2 = document.getElementById('<%=text2.ClientID %>').value;
                  PageMethods.ScanComplete(txt1, txt2, OnSuccess, OnFailure);

              }
          }
 </script>

---

My WebMethod in the code behind (cut down for simplicity) :

HTML Code:

---

  [WebMethod]
        public static string ScanComplete(string data1,string data2)
        {
            string returnValue = string.Empty;
            returnValue = data1 + " and " + data2 + " have been saved.";
            return returnValue;
        }

---

Basically when the user hits carriage return on the second textbox 'text2' the contents of text1 and text2 are sent to the [WebMethod], concatenated and returned to be displayed in a label.

This works great on my dev machine but when I try it from any another machine the label does not appear. It's been a while since I have done any web work so am a wee bit confused.

Anyone have any ideas why this is happening?

Thanks in Advance

Further Issues. The following code checks for a carriage return when entering in textbox1 ('text1') and shifts focus to textbox2 ('text2').

function CheckForReturn() {
if (event.keyCode === 13) {

document.getElementById('text2').focus();
}
}


This works well in IE 10/11 but in firefox does nothing at all.

It's not a huge issue though as the users will only be using IE.

https://jsfiddle.net/tdzs93jb/3/

You need to pass the event argument into your event handler for it to work in Firefox.