Advice Please: No Stereo on a System Set-Up Disc

I used a system set-up disc on my hi-fi recently and one of the features on the disc is a phase test, which is designed to produce sound on the left speaker and then on the right speaker. The objective, I presume, is to establish whether your speakers are wired correctly. On my stereo system, the sound does not shift from the left to the right speaker, but comes through both speakers. The amp and speakers are wired correctly. Any ideas what is happening here?

Ps. My Musical Fidelity A5 amp does not have a balance button.