jQuery: JSON callback function never reached

开发者_Python百科I'm requesting a page via JSON but never reach the callback-function. Does someone know why this is happening?

jQuery.getJSON("'. $dnd_fileupload_dir .'dnd-medialink.php?format=json&jsoncallback=?", function(data){  
    alert("lalala");
});

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Use firebug to see what's going on. Either the request URI is incorrect and there is a 400 error, or the response is not valid JSON.

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I would suggest downloading fiddler tool and using it to watch what is sent over http. A simple search on google will get you to the fiddler website