FOG: Creating instances in AWS fails

We are seeing below error when ever we try to create instances in AWS. Sometime it succeeds but most of the time it is throwing error. If we try to create 5 nodes it creates, 1 or 2 and fails on other.

Failure/Error: conn.servers.length
Excon::Error::Socket:
XML declaration allowed only at the start of the document (Nokogiri::XML::SyntaxError)

This is the way I'm creating the instances.

     Fog::Compute.new(
        :provider               => 'AWS',
        :region                 => @region,
         :use_iam_profile              => true
      )

 def valid_connection?(conn)
     conn.servers.length
     true
   rescue Excon::Errors::Forbidden, Excon::Errors::Unauthorized, Fog::Compute::AWS::Error
     false
   end

I tried to enable the debug logging as well but it does not show much info.