Blend not working with Fuzz

[mwynwood]

I have just built this, and it works great with my Boss Tremolo, but when I use it with a fuzz, it doesn't work as it should.
The blend knob functions like a volume knob.

http://tagboardeffects.blogspot.com.au/2012/01/mini-blend-jfet.html

Is this because of some weird interaction between the buffer and the fuzz circuit, or am I doing something wrong?
Thanks!

[mwynwood]

Whoops, I just realised that I posted this in the wrong area! Sorry!