Volcanic Backup, Amazon S3 bucket, error meassage,

Trying to set up Volcanics Automatic Backup.

Getting this error message:
Warning: shell_exec() [function.shell-exec]: Cannot execute using backquotes in Safe Mode in………ect., ect.

I went to my hosts cPanel>php configuration> and it appears that safe mode is off.
Language Options safe_mode Off

I just got W3 Total Cache set up and it is communicating with Amazon so I know my access key and secret key are correct.

I set up a “bucket” manually from amazon web service console, so bucket definitely exists.

While setting up W3tc with Amazon s3 I was getting this error message:
Error: Unable to list buckets (S3::listBuckets(): [SignatureDoesNotMatch] The request signature we calculated does not match the signature you provided. Check your key and signing method.).

I signed up for cloudfront and was able to make w3tc work.

Considering that safe mode is apparently off (although is it?), and that i was having an issue with the “bucket” in w3tc, and I need to use the bucket in automatic backup I am assuming this is the location of the problem. And considering that I was unable to resolve the bucket issue with w3tc then it might still be haunting me when trying to set up automatic back up.

Whatever the problem is I would appreciate any ideas on what might be going on.

So far I have gone back through my aws account multiple times to see if anything is amiss and I can’t find any problems.