title: TeamCity: Type or namespace cannot be found, but the reference exists and my project compiles locally
body: <p>I have an ASP.net MVC 3 project. We're using TeamCity, and up until now everything has checked in fine. All of a sudden today, I did a checkin, and the TeamCity build failed. It said I was missing a using directive or assembly reference and threw a compilation error. </p>
  
  <p>The project on my local machine builds successfully. I rebuilt it several times to make sure. I checked the reference and it's there. I checked the .csproj file and it has the reference there too. I checked bin; it's there. I even RDPed into the server where our site is deployed and checked the bin there, and the dll file is there too. </p>
  
  <p>I don't understand why it's not working, I haven't changed anything in the particular files it says are missing the assembly reference in weeks, I had a successful checkin on TeamCity yesterday, the dll file exists everywhere it's supposed to, and my project builds. I even did a hard reset to the last commit I made that checked in successfully, added my changes back in (which had nothing to do with the reference problem, all my changes were in a .js file), and checked that in, but I got the same compilation error. </p>
  
  <p>Does anyone have any idea what's going wrong, or at least what I might try to resolve this?</p>
  
  <p>edit: There are no path files being used here, the file in question is a .dll file, which I added by clicking "Add reference" on the project. I checked the Github repository and the .dll file is in the bin folder</p>