Exception when using httparty for itunes verification

Here is a piece of code I wrote to implement itunes_verification.

http://gist.github.com/raw/622038/b32accd30e86f7c714f2cffefd19857f558c8d97/gistfile1.rb

ItunesVerification.verify_apple_receipt("wefwfrw")

But, its always throwing {"exception"=>"java.lang.NullPointerException", "status"=>21002} from the itunes server.

#<HTTParty::Response:0x46d59a8 @parsed_response={"exception"=>"java.lang.NullPointerException", "status"=>21002}, @response=#<Net::HTTPOK 200 Apple WebObjects readbody=true>, @headers={"x-webobjects-loadaverage"=>["0"], "x-apple-application-site"=>["SB"], "expires"=>["Thu, 14 Oct 2010 04:24:12 GMT"], "connection"=>["keep-alive"], "edge-control"=>["no-store", "max-age=0"], "pod"=>["100"], "date"=>["Thu, 14 Oct 2010 04:24:12 GMT"], "x-apple-max-age"=>["0"], "x-apple-application-instance"=>["1000407"], "x-apple-woa-inbound-url"=>["/WebObjects/MZFinance.woa/wa/veri开发者_开发问答fyReceipt?output=json&receipt-data=d2Vmd2U%3D%0A"], "content-length"=>["62"], "set-cookie"=>["Pod=100; version=\"1\"; expires=Sun, 14-Nov-2010 05:24:12 GMT; path=/; domain=.apple.com", "mzf_in=1000407; version=\"1\"; path=/WebObjects; domain=.apple.com"], "x-apple-lokamai-no-cache"=>["true"], "cache-control"=>["no-transform", "private", "no-cache", "no-store", "must-revalidate", "max-age=0"], "pragma"=>["no-cache"]}>

Also, the string I pass is encoded to Base64.

I have tried other options like changing the key from "body" to "query".

This is very urgent and any help will be greatly appreciated.

Thanks

There already is a similar problem posted, check it out here, perhaps the suggestions there can help you.