I just bought a brand-new Hum Debugger. When I engage the unit, I get a pinging sound. It sounds kind of like an auto-wah, or a Dalek from Doctor Who.
What am I doing wrong? Why am I getting this strange sound?

I plug my guitar straight into the unit, and from there straight into the amp. Amp and unit are plugged into the same outlet. I’m using the adaptor that came with the unit