What MG version r u on (the version of MG you have installed using the .exe since that's where the pipeline tool will get run from)?
What machine are you compiling on?
What are the properties of your content-file?
Here are mine:
As you see your code is compiling fine on my setup. (I just copy-pasted it into the file ps_4_0_level_9_1_register.fx.)
I'm using MG v184.108.40.2068.
I'm on a Windows machine.
After reading your message again...
You are absolutely sure that you've compiled the right file, since the error message says:
Invalid Profile "", Pixes shader 'Pix... where the level you actually declared should be within the quotes, but these are empty in your error message.
So it suggests that the file you compiled looked something like this:
PixelShader = compile vs_4_0_level_9_1 PixelShaderFunction(); or some other invalid string (here it is the declaration for the vertex-shader instead the pixel-shader) instead of that:
PixelShader = compile ps_4_0_level_9_1 PixelShaderFunction();
I get your error with that.
But of course it could be a bug in MG.