Pedal works alone but not with other pedals.

[nguitar12]

Hi everyone recently I breadboard-ed a compressor circuit based on the following schematic:

http://www.aronnelson.com/gallery/main.php/v/johan_0/LA_Light_simplified_for_stompbox_use.gif.html

Pedal works alone but will not work with other pedal. One thing I found weird is that this circuit will work properly only if I tie the sleeve of the I/O jack to the virtual ground rather than the real ground, which is unusual compare to most pedal I built before. I think this might  be the reason why this pedal doesn't work with other pedal? Can someone please suggest a solution to this?

Thanks