Amazon Web Services - PHP SDK - S3 putBucketAcl() returns Bad Request

I'm trying for HOURS to make s3->putBucketAcl() works, without any success.

I'm having various exception errors, and I'm currently blocked on this one:

400 - Bad Request - This request does not support content

Here are params I'm using:

Array
(
    [ACL] => private
    [Owner] => Array
        (
            [Id] => 086caca9fb91331dbedb9abbed21c0db5a940138c1ac6f6297f042550ba553b5
        )

    [Grants] => Array
        (
            [0] => Array
                (
                    [Grantee] => Array
                        (
                            [ID] => 476105dd3f400339485f36296bde3563692d134e4c9a507e9ce63f114fcb2e14fdedff50140d41993f45137d0d049352
                            [Type] => CanonicalUser
                        )

                    [Permission] => FULL_CONTROL
                )

        )

    [Bucket] => kaemo
)

By the way, what is the difference between 'ACL' => 'string' asked and grantees permissions?

I just want to update my buckect ACLs (add new ACL access).

Thanks for your help... AWS API => nights of headache !!!