ASP.Net Web Forms Application Can't Find Namespace

I was creating a test Web Forms application and added some existing code files.

I first added them to the app_code folder, but in there they could not find the OracleDataClient namespace.  I found something that said to move the code file out of app_code and that fixed the Oracle problem.

Then when I would reference classes in those files the page code did not recognize the namespace.

After a while of searching I found someone who said to right click on the files and view properties.

The property they said to look at was Build Action.  My file was set to Content and I saw to change it to Compile.  That fixed it.