Derelict SFML2 - structs are forward referenced

[Lucien via Digitalmars-d-learn]

Hello.

I want to use Derelict-SFML2 to create a simple window.
But when I compile (linked with dub and derelict-util), I have 
the following error:

src/app.d(30,20): Error: variable myproject.main.window no 
definition of struct sfRenderWindow
../../../.dub/packages/derelict-sfml2-3.0.1/source/derelict/sfml2/graphics.d(56,1): Error: struct derelict.sfml2.graphics.sfRenderWindow unknown size
src/app.d(31,5): Error: struct sfRenderWindow is forward 
referenced
src/app.d(32,12): Error: struct sfRenderWindow is forward 
referenced
src/app.d(35,16): Error: struct sfRenderWindow is forward 
referenced
src/app.d(38,17): Error: struct sfRenderWindow is forward 
referenced

My code: http://pastebin.com/1svZAB22

Is it a bug in Derelict-SFML2 or want did I do false ?

Hoping that you understood me with my bad English :)