aws s3 not able to delete the object by code php

I am putting a object in my AWS S3 basket by using following code.

        $temp = explode(".", $_FILES["file"]["name"]);
        $_FILES["file"]["name"] = $newfilename = round(microtime(true)) . '.' . end($temp);

        $filepath = $_FILES['file']['tmp_name'];
        try {
            $result = $this->Amazon->S3->putObject(array(
                'Bucket' => 'mytest.sample',
                'ACL' => 'authenticated-read',
                'Key' => 'files/image/' . $id . '/' . $newfilename,
                'ServerSideEncryption' => 'aws:kms',
                'SourceFile' => $filepath,
                'ContentType' => mime_content_type($filepath),

            ));
        } catch (S3Exception $e) {
            echo $e->getMessage() . "\n";
        }

and it is working fine. files are uploading but when I try to delete the file empty response I am getting. here is the code used for deleting object.

try {
                $result = $this->Amazon->S3->deleteMatchingObjects(array(
                    'Bucket' => 'mytest.sample',
                    //'Key' => 'files/image/' . $id . '/' . $fileName['Attachment']['attachment'],
                    'Key' => 'files/image/45/1441026402.docx', //static path for checking.
                    'VersionId' => 'latest',
                ));
            } catch (S3Exception $e) {
                echo $e->getMessage() . "\n";
            }

I tried below method too

   try {
        $result = $this->Amazon->S3->deleteObject(array(
            'Bucket' => 'mytest.sample',
            //'Key' => 'files/image/' . $id . '/' . $fileName['Attachment']['attachment'],
            'Key' => 'files/image/45/1441026402.docx',
            'VersionId' => 'latest',
        ));
    } catch (S3Exception $e) {
        echo $e->getMessage() . "\n";
    }

Is there any permission issue?