注意：Graph API的未定义索引php sdk

I send a Facebook request using Graph api and i get the Array below as a result. However when i am trying to execute the code:

$a=count($Obj_1['events']->data);

I get the following message

Notice: Undefined index: events

I have tried everything like:

$Obj_1[0]->events->data
$Obj_1->events->data                 
$Object[0]->['events']->data

and googled anything trying to figure this out. I am trying to get rid of the Notice because the script runs as intended... Pls help :)

 Array(
        [events] => stdClass Object
            (
                [data] => Array
                    (
                        [0] => stdClass Object
                            (
                                [name] => 
                                [start_time] => 
                                [timezone] => 
                                [id] => 
                            )

                    )

                [paging] => stdClass Object
                    (

                       )
            )
        [id] => 
    )

Try replace: if print_r($Obj_1); line do work then replace following.. From

$a=count($Obj_1['events']->data);

To

$tmpObj=$Obj_1["events"];
$a=count($tmpObj->data);