gtkd.lib: Error 43: Not a Valid Library File

[Enjoys Math via Digitalmars-d-learn]

I get this message either compiling at command line -or- in 
VisualD.

At command line when I add -m64, I get another error:


C:\MyProjects\___LIGHTSHOWAPP\___LIGHTSHOWAPP>dmd -m64 main.d 
-L+gtkd
LINK : fatal error LNK1181: cannot open input file '+gtkd.obj'
--- errorlevel 1181