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jQuery Mobile 1.2.0 is not compatible with jQuery 1.8.3. Drop back to 1.8.2.jquery 1.8.3, jquery mobile 1.2.0
Debug your AJAX first. Make sure that you understand what the server requires and that it is returning what it is supposed to return.It appears, though, from your posting, that the server is returning an error. You need to find out why the server is returning an error