google app quickstart.php example how to change sheet

So i have run through the guide of how to read data from a google sheet using their API. All works fine until i want to read from any sheet other than the one given in the example.

is there something else that i need to change as when I update the spreadsheet id to one of mine i just get the following

Fatal error: Uncaught exception 'Google_Service_Exception' with message   '{
  "error": {
"code": 400,
"message": "Unable to parse range: Class Data!A2",
"errors": [
    "message": "Unable to parse range: Class Data!A2",
    "domain": "global",
    "reason": "badRequest"

Any help would be greatly appreciated.

sorry guys the issue was that i was declaring the range wrong problem now sorted.