Error in usort shown by Dreamweaver
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In the following code, dreamweaver shows error, but I couldn't detect whats wrong with it. Please help me with that. 

No error displayed during execution of script and code is giving me the required results.. .Whats wrong in dreamweaver...

    usort($hotProp, function ($a, $b) { return ($a[0]['Property']['count'] > $b[0]['Property']['count']); });