Can't add date and time properly

I try to add date and time into my database but I have probems:

First: I create a form:

<div class="row">
<div class="form-group col-md-6">

    {!! Form::label('roba_spremna','The cargo is ready:') !!}
    {!! Form::text('roba_spremna', null, ['class'=>'form-control']) !!}
</div>
<div class="form-group col-md-6">

    {!! Form::label('auction_end','Auction close at:') !!}
    {!! Form::text('auction_end', null, ['class'=>'form-control']) !!}
</div>
</div>

After that I add bootstrap-datetimepicker (js library):

$( document ).ready(function() {
                $(function () {
                    $('#roba_spremna, #auction_end').datetimepicker();
                });
            });

and at Article model I write:

 protected $fillable = [
        'title',
        'body',
        'roba_spremna',
        'auction_end'
    ];

    protected $dates = [
        'roba_spremna',
        'auction_end'
    ];

    public function setRobaSpremnaAttribute($date){
        $this->attributes['roba_spremna']= Carbon::createFromFormat('Y-m-d', $date);
    }

Now When I try to store date with time at my database so when I submit form I get this error: InvalidArgumentException in Carbon.php line 425: Unexpected data found. Unexpected data found. Trailing data

http://i.imgur.com/V1imBwC.png

How I can solve my problem?