[jQuery] newbie: Error on JSON parsing

[loste]

Hello,
I'm trying to parse a Json string received by $.getJSON().

I can receive the string but firebug gives me an "invalid label"
error.
I think it is because the string is an hash array with a number as
first label, but I'm not sure.

This is the string:
{"15":{"id":15,"x":0.4589937586135409,"y":
0.8324914620560137,"z":-0.9435707004102728,"rawData":"1256204002860 13
-442866538 18392602 647462767 314 1777206957 -1664784174 "}}

and this is the non-working code:

 $.getJSON(url+"&jsoncallback=?", function(received){
        stateChanged(received);
    });

Any Idea on how can I import it?

Thank you,
loste