CS0234 for Referenced Local Project

I am receiving the

CS0234: The type or namespace name开发者_StackOverflow '...' does not exist in the namespace '...' (are you missing an assembly reference?)

I notice when I click on "Show Detailed Compiler Output" that the project nor its binary output is referenced in the csc build command. It was working fine before but after I make a few changes in code, my app started to break. Any help would be greatly appreciated!

It's also worth noting I'm using ASP.NET MVC 2.

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It ends up ASP.NET is not so good at resolving references. I ended up adding my assembly to the web.config section and all was good.

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Is this a compile time error? I had a similiar error when I made somechanges to my view. If you did any changes in your view and having this kind of issue - let me know, I`ll write how to fix that.