PostFX does not work

[Wurstinator]

Hi,
I've got a problem when using the GLSL feature.
I have created a test project which shows a random number of red semi-transparent circles and on top of that a Sprite.
http://img580.imageshack.us/img580/8747/screenbw.png

But now I tried to create and use a shader (grayscale) but it doesn't work.
My code: http://wurstinator.pastebin.com/zKk6xaNa (I know it's messy but it is just a test project
My shader: http://wurstinator.pastebin.com/b3pWADCd

When I apply the shader the circles are still a bit red:
http://img696.imageshack.us/img696/7233/screenkopie.png

Hope someone can help =(

/edit: I'm using version 1.6

/edit 2: Solved it, seems like the alpha value has to be 1.

[Hugo]

Nice. ,mind posting the effect code on here? I have to learn this whole"post fx" thing cause I am a dreamer with dreams, one of them is upload a bunch of cool post fx effect files on to sfml.org