Ruby aws-sdk gem configuration Hash is converted to String - ruby-on-rails

Question

I am trying to use amazon S3 for storing and retrieving files from my rails application, have setup the changes in configuration file for aws_credentials, but what is supposed to by sent as hash to the below configuration.rb file is being sent as string.
Credentials in development.rb in my application is as follows:
:s3_credentials => {
:bucket => "mybucketname",
:access_key_id => "MYACCESSKEYID",
:secret_access_key =>"MYSECRECTACCESSKEYID"
}
The options object supposed to be a hash is being sent as string like this:
"bucket:mybucketname access_key_id:MYACCESSKEYID
secret_access_key:MYSECRECTACCESSKEYID"
That is causing the issue with the below error:
/.rvm/gems/ruby-1.9.3-p484/gems/aws-sdk-v1-1.64.0/lib/aws/core/configuration.rb:292:in `with': undefined method `inject' for (NoMethodError)
The part of error occurence in configuration.rb file in the gem is:
def with options = {}
options = options.inject({}) {|h,kv| h[kv.first.to_sym] = kv.last; h }
values = supplied.merge(options)
if supplied == values
self # nothing changed
else
self.class.new(values.merge(:__created__ => #created.dup))
end
end
I have no idea where the object type getting modified, i even tried using the credentials through yaml file but still the same issue. Its working in my colleague's machine in another project, but somehow for my project i am finding difficult with this issue. Advance thanks for any help.