db.runcommand working on mongoshell giving result but not working with php

This is the query with php for search according to latLong also created 2d sphere index feild .but not working.

$db = DB::getMongoDB();
$r = $db->command(array( 'geoNear' => "sale_event",'near' => array( 'type' => "Point", 'coordinates' => array('76.7171945','30.7291196')), 'spherical' => true, ));

This command is working fine on mongo shell and giving results .

db.runCommand(    {      geoNear: "sale_event",      near: { type: "Point", coordinates: [ 76.7171945,30.7291196 ] },      spherical: true,        } )

Here I am pasting result of mongo shell after running the above command in shell:

{
"results" : [
    {
        "dis" : 0,
        "obj" : {
            "_id" : ObjectId("568e01fc04896fcd208b4575"),
            "seller_rating" : "4.5",
            "status" : "1",
            "title" : "we're",
            "quantity_ordered" : "100",
            "sale_event_longitude" : 76.7171945,
            "image" : "test image",
            "repeat_every_friday" : false,
            "price_in_primary_currency" : "1325",
            "repeat_every_sunday" : false,
            "quantity_available" : "13455",
            "pick_up_or_delivery" : "Pickup",
            "primary_currency" : "SGD",
            "quantity_delivered" : "10",
            "delivery_radius_in_km" : "No delivery",
            "repeat_every_thursday" : false,
            "sale_event_latitude" : 30.7291196,
            "repeat_every_saturday" : false,
            "type" : "Chinese",
            "restriction" : "Vegetarian",
            "repeat_every_monday" : false,
            "seller_address_id" : "568e01a804896fcd208b4570",
            "seller_user_id" : "568e008204896fcd208b456f",
            "repeat_every_wednesday" : false,
            "item_id" : "568e01d904896fcd208b4572",
            "repeat_every_tuesday" : false,
            "image_thumbnail" : "test image 2",
            "latLong" : [
                76.7171945,
                30.7291196
            ],
            "description" : "Where'd",
            "updated_at" : ISODate("2016-01-07T06:13:16.152Z"),
            "created_at" : ISODate("2016-01-07T06:13:16.150Z"),
            "pickup_date_delivery_and_time_from" : ISODate("2016-01-07T11:40:34Z"),
            "pickup_delivery_date_and_time_to" : ISODate("2016-01-09T11:40:36Z")
        }
    },
    {
        "dis" : 244708.75191385587,
        "obj" : {
            "_id" : ObjectId("568e01eb04896fcd208b4574"),
            "seller_rating" : "4.5",
            "status" : "1",
            "title" : "we're",
            "quantity_ordered" : "100",
            "sale_event_longitude" : 77.0999578,
            "image" : "test image",
            "repeat_every_friday" : false,
            "price_in_primary_currency" : "1325",
            "repeat_every_sunday" : false,
            "quantity_available" : "2345",
            "pick_up_or_delivery" : "Pickup",
            "primary_currency" : "SGD",
            "quantity_delivered" : "10",
            "delivery_radius_in_km" : "No delivery",
            "repeat_every_thursday" : false,
            "sale_event_latitude" : 28.5561624,
            "repeat_every_saturday" : false,
            "type" : "Chinese",
            "restriction" : "Vegetarian",
            "repeat_every_monday" : false,
            "seller_address_id" : "568e01b804896fcd208b4571",
            "seller_user_id" : "568e008204896fcd208b456f",
            "repeat_every_wednesday" : false,
            "item_id" : "568e01d904896fcd208b4572",
            "repeat_every_tuesday" : false,
            "image_thumbnail" : "test image 2",
            "latLong" : [
                77.0999578,
                28.5561624
            ],
            "description" : "Where'd",
            "updated_at" : ISODate("2016-01-07T06:12:59.263Z"),
            "created_at" : ISODate("2016-01-07T06:12:59.261Z"),
            "pickup_date_delivery_and_time_from" : ISODate("2016-01-07T11:40:15Z"),
            "pickup_delivery_date_and_time_to" : ISODate("2016-01-08T11:40:17Z")
        }
    }
],
"stats" : {
    "nscanned" : 20,
    "objectsLoaded" : 2,
    "avgDistance" : 122354.37595692794,
    "maxDistance" : 244708.75191385587,
    "time" : 3
},
"ok" : 1

}

Now am executing code in php laravel :

$db = DB::getMongoDB();
$r = $db->command(array( 'geoNear' => "sale_event",'near' => array( 'type' => "Point", 'coordinates' => array('76.7171945','30.7291196')), 'spherical' => true, ));

Response am getting :

Array
(
 [ok] => 0
 [errmsg] => can't find ns
)

I am using mongodb.

via Chebli Mohamed