Asp.net website: cannot find extention method
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I have ASP.net website. In `App_Code` folder I have class that has extention methods. When running this site from visual studio, everything works. However on my IIS 7 server, i received the following error:

>  CS1061: 'System.Data.SqlClient.SqlDataReader' does not contain a definition for 'SafeGetString' and no extension method 'SafeGetString' accepting a first argument of type 'System.Data.SqlClient.SqlDataReader' could be found (are you missing a using directive or an assembly reference?)

But the file containing this extention methods is in App_Code folder. Am I missing something important?