Another annoying programming thing

Mostly for my own benefit, but in case anyone comes across this same issue, I was having a problem with a C# solution claiming that a type was missing from a namespace, something like this:

"The type or namespace 'type' does not exist in the class or namespace 'namespace' (are you missing an assembly reference?)"

Turns out the reason for this was that the build configuration was targeting the wrong processor in some of the projects. I set them all to the same processor, and Bob was my uncle!