Nodejs v0.8.20 with mongoosejs for nodejs for fetch query error with no response

I used nodejs 0.8.20 with mongoosejs for nodejs for fetch query. First time it will fetch query with data result. But for the next time with same query doesn't get any response or error messages. It will show always blank.

Please let me know, if i did anything wrong with this code.

This is the code.

var schema_reviews =  {
"approved"      :"Number",
"comment"       :"String",
"item_id"       :"Number",
"timestamp"     :"Number",
"user_id"       :"Number",
"user_type"     :"String",
"username"      :"String"}

var reviews_schema      = new mongoose.Schema(schema_reviews);
var itemid = 54;
var reviews_model = db.model('reviews',reviews_schema);
reviews_model
.find({ 'item_id': itemid },function(err,review_lists){
    socket.emit('reponse_reviews',review_lists);
});