Publication date not show in the Edit page

After creating a blog post successfully when i try to update the all the other column data are passed except the published_at if i enter the date manually it gives this error "InvalidArgumentException Data missing " and if i just click on the draft it will save without error

Edit page>

 <div class="box-body">
         <div class="from-group {{ $errors->has('published_at')  ? 'has-error' : '' }}">
                {!! Form::label('published_at','Published Date') !!}
   {!! Form::text('published_at', null, ['class'=>'form-control datepicker-here ', 'placeholder' => 'Y-m-d H:i', 'id' => 'date' ]) !!}

                 @if($errors->has('published_at'))
  <span class="help-block">{{$errors->first('published_at')}}</span>
                                @endif
                            </div>
                        </div>

                        <div class="box-footer clearfix">
                            <div class="pull-left">
                                <a id="draft-btn" href="" class="btn btn-default">Draft</a>
                            </div>
                            <div class="pull-right">
                                {!! Form::submit('Publish', ['class'=>'btn btn-primary']) !!}
                            </div>
                        </div>
                    </div>
                </div>
                {!! Form::close() !!}
            </div>
            <!-- ./row -->
        </section>
        <!-- /.content -->
    </div>
@endsection

script

    <script type="text/javascript">
        $('#draft-btn').click(function (e) {
            e.preventDefault();
            $('#published_at').val("");
            $('#post-form').submit();
        });
</script>
@stop

Create Page

<td width="70">
                {!! Form::open(['method'=>'DELETE', 'route' =>['blogs.destroy', $post->id]]) !!}
                <a title="Edit" class="btn btn-xs btn-default edit-row" href="{{route('blogs.edit', $post->id)}}">
                    <i class="fa fa-edit"></i>
                </a>

                <button class="btn btn-xs btn-danger delete-row" href="{{route('blogs.destroy', $post->id)}}">
                    <i class="fa fa-trash"></i>
                </button>
                {!! Form::close() !!}
            </td>

Don't know what i'm doing wrong here. please help