unable to set request header in as3

hi all,

I did face the similar issue and i cant set request headers in flash AS3. Actually i m trying to download file from S3 Amazon Bucket, which can only be allowed if custom header is set in a request. I m trying to set that but when I check the request Packets from Etheral or WireShark, the request doesnt contain any of mine custom header.

here is my flash download...