关于ec2的ebs永久性存储有关问题

关于ec2的ebs永久性存储问题
大家好，小弟今天做ec2的ebs久性存储，在执行@ec2.describe_images_by_owner([ENV['AWS_ACCOUNT_NUMBER']])时候，报错：如下：
 ERROR -- : #<NoMethodError: private method `gsub' called for nil:NilClass>
/usr/lib/ruby/1.8/cgi.rb:342:in `escape'/usr/lib/ruby/gems/1.8/gems/right_aws-1.9.0/lib/ec2/right_ec2.rb:139:in `generate_request'/usr/lib/ruby/gems/1.8/gems/right_aws-1.9.0/lib/ec2/right_ec2.rb:139:in `collect'/usr/lib/ruby/gems/1.8/gems/right_aws-1.9.0/lib/ec2/right_ec2.rb:139:in `generate_request'/usr/lib/ruby/gems/1.8/gems/right_aws-1.9.0/lib/ec2/right_ec2.rb:177:in `ec2_describe_images'/usr/lib/ruby/gems/1.8/gems/right_aws-1.9.0/lib/ec2/right_ec2.rb:223:in `describe_images_by_owner'(irb):31:in `irb_binding'/usr/lib/ruby/1.8/irb/workspace.rb:52:in `irb_binding'/usr/lib/ruby/1.8/irb/workspace.rb:52.join('
')}
E, [2011-06-21T21:27:26.501962 #2319] ERROR -- : Request was: /?Action=DescribeInstances&Signature=kaUy28l3qPgBq%2Fzsf3IumiofDs0%3D&Version=2008-08-08&AWSAccessKeyId=AKIAJ3E66DSIJWS672XQ&SignatureVersion=1&Timestamp=2011-06-22T01%3A26%3A12.000Z
E, [2011-06-21T21:27:26.502027 #2319] ERROR -- : Response was: 200 -- OK -- <?xml version="1.0" encoding="UTF-8"?>
不知道什么原因，请大家帮帮忙！

------解决方案--------------------
呵呵！