Why my same ".s3cfg" file is not working on different machines

I have server ec2 instance where I got error :

$ sh ami-backup.sh 
----------------------------------
   Thu Sep 24 10:37:47 UTC 2015   
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Unable to locate credentials. You can configure credentials by running "aws configure".

Same script worked on my local machine so I coped ".s3cfg" to that server still it gives same error "Unable to locate credentials"

On my local machine :

ashish@ashishk:~$ aws ec2 describe-instances --filters Name=vpc-id,Values=vpc-xxx |   awk '{ print $8 }' | sort -n   | grep  "i-" 
i-127fb8df
i-1effb6d3
i-29efe0e4
i-29fd04e4
i-d5888618

On my server (ec2 instance) with same ".s3cfg" :

$ aws ec2 describe-instances --filters Name=vpc-id,Values=vpc-xxx |   awk '{ print $8 }' | sort -n   | grep  "i-" > /tmp/instanceid.txt
Unable to locate credentials. You can configure credentials by running "aws configure".

Why my same ".s3cfg" file is not working on different machines ! Please let me know what is wrong here !