Allan,
First of all, are the jumpers soldered properly?
If so, try to test to see if the volume pot is connected properly on the PCB. To do this see if you have continuity between one of the side pins of the pot (the one on the left, depending on how the board is turned) and ground; test to see if the other side pin is connected to one of the pins of C4; then (while the pedal is engaged, ie the red light is ON beside the bypass switch) test to see if the center pin is connected to the output jack tip (or better yet, one of the pins of the relay closest to the edge of the board). For more details look a the schematic in the back of the manual. If all these are making connection then then the volume pot is connected properly and the issue is something else, so start working through the troubleshooting guide.
Let me know what you find.
-Brach