For all interested parties if you run into this error after compiling a custom module…
Dotnetnuke BC30451: Name ‘Initialize’ is not declared.
It is most likely you didn’t change your reference paths in Visual Studio.
Brian Dukes ran into this problem, discussed here. His solution was to copy a fresh copy of the core Dotnetnuke.dll into your root /bin folders but if you don’t change the reference paths in Visual Studio, each time you compile your custom module the Dotnetnuke.dll will be replaced with the an older one if it exists.
Don’t forget to change the reference paths for both your main module project and the corresponding sqldataprovider project because it will also have the same reference paths.
HTH, Thuan.