I am trying to create a class library using some classes that I created in another project. One of the classes uses images and needs the `System.Drawing` namespace. However, when I try to copy the code from my project into a new class in my class library, I get an error saying *the image object does not exist in the current context*, and 

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> The type or namespace name "Drawing" does not exist in the namespace System(are you missing a using directive or an assembly reference?)
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It works fine in the other class as part of the other project. Why would this be?