Volume control mystery

[brett]

Hi.  I built a modified Bluesbreaker (from Tonepad.com) a while back for a guy who lives in the outback.  He tells me that the volume control doesn't work.  Weird thing is that when I get it back, the volume control works fine for me.  The Bluesbreaker uses the usual log pot (100k) as a volume control.  I feel that the answer must be so simple I'm missing something.   :oops:    

Any ideas?

[ErikMiller]

What is the next device in his signal chain? That can have an effect on volume controls. Does it work if he runs it directly into his amp? Through a different amp?

[brett]

His next device is a Boss BluesDriver.  Then into a Marshall amp.

I'm wondering if the indicator light isn't faulty.  Maybe the lamp is glowing and he thinks he's got an effect, but it's actually bypassed?