httpModules code not being executed on the server

I use VS 2010 and IIS 7. The query string that is sent to my page is encrypted, and to read the encrypted string, I followed http://madskristensen.net/post/HttpModule-for-query-string-encryption to encrypt query string. In the web.config, I put this
<system.web> <httpModules> <add type="QueryStringModule" name="QueryStringModule" /> </httpModules> </system.web> To test, I enter something like this on the URL For ex: http://localhost/mySite/myPage.aspx?enc=azwwWa6dlVzHnx9R8Ma33SI= It works when I test it on my machine from Visual Studio, but when I published it to the server (also uses IIS 7), it doesn't execute the code in QueryStringModule.
At first, it gave me an error "HTTP Error ...