Exerb4.2.0 don't work with ruby1.8.7 and yaml

There is my test.rb:
require ‘yaml’
config = YAML::load(File.open(“config.yml”))

and there is my config.yml:
topic: forum-39-thread-11173510-1-1

“mkexy test.rb” and “exerb test.exy” can execute all right and generate
but when I execute test.exe,it raise an error:
yaml.rb:9:in `require’: Win32API Error #127
from yaml.rb:9
How can I fix it?Any help will be appreciated!