Compiling ASP with VBC.exe

I'm having some issues compiling an asp.net project with vbc.exe

my commandline code is:
vbc /t:library /out:C:/Inetpub/wwwroot/WebApplication1/bin/WebApplication1 /r:System.dll etc C:\Inetpub\wwwroot\WebApplication1\*.vb

That runs without raising any errors, and the dll is created. However when I try to open it from a browser, I get the Parser Error, Could not load type 'WebApplication1.Global'

However, when compiled through VS.Net (F5), it runs fine. The Dll created with vbc.exe is slightly smaller than the dll created through VS.Net. Does anyone know the reason why this is?

What is the 'etc' for?