Warning: json_encode(): type is unsupported, encoded as null in couchbase -

i have installed couchbase on remote linux machine, , want access on windows using php scripts. using putty on windows 7.

my code below:

if(extension_loaded('couchbase')) {         $cluster = new couchbasecluster('http://23.99.27.188:8091');       $bucket = $cluster->openbucket('beer-sample');       $get = $bucket->get('demo');       echo json_encode($get); }  else  {         echo "error";     }   

but gives error:

warning: json_encode(): type unsupported, encoded null in c:\xampp\htdocs\couchbase\index.php on line 28