Please give me a hand on Google Adwords API

Hi All:
Does anyone familiar with the Google Adwords api? Recently, I am using
the Google Adwords api and I found there were some problems existed in
the sample code. The sample code I used is download_report.rb from
201101 version folder, I used this file to download the report that I
have defined in ReportDefinitionService with the report_definition_id
had been given; however, the problems occurred as following:

C:/Ruby187/lib/ruby/gems/1.8/gems/google-ads-common-0.2.1/lib/ads_common/api_config.rb:279:in
get_wsdl_base': undefined method[]’ for nil:NilClass (NoMethodError)
from
C:/Ruby187/lib/ruby/gems/1.8/gems/google-adwords-api-0.1.2/lib/adwords_api/api_config.rb:264:in
report_download_url' from C:/Ruby187/lib/ruby/gems/1.8/gems/google-adwords-api-0.1.2/lib/adwords_api/extensions.rb:294:inget_report_url’
from
C:/Ruby187/lib/ruby/gems/1.8/gems/google-adwords-api-0.1.2/lib/adwords_api/extensions.rb:211:in
download_report' from C:/Ruby187/lib/ruby/gems/1.8/gems/google-adwords-api-0.1.2/lib/adwords_api/extensions.rb:193:indownload_report_as_file’
from
C:/Ruby187/lib/ruby/gems/1.8/gems/google-adwords-api-0.1.2/lib/adwords_api/v201101/ReportDefinitionServiceWrapper.rb:372:in
download_report_as_file' from D:/USER/022294/ÎÒµÄÎĵµ/NetBeansProjects/Application1/CampaignReport/lib/download_report.rb:42:indownload_report’
from
D:/USER/022294/ÎÒµÄÎĵµ/NetBeansProjects/Application1/CampaignReport/lib/download_report.rb:49

Does anyone can help me solve this? I’ve tried to reinstall all the gems
that required for running this code, but the problems may not coursed by
the Ruby gem version, I guess so.