A Captain approaching BQK noticed aircraft lights on the opposite runway and executed a go around only find out that the First Officer was broadcasting CTAF position reports on an incorrect frequency.

Narrative

We did everything right; except one thing; but good 'heads-up' helped get things right: We were on a left base on visual approach to Runway 7. (This runway was chosen due to the calm winds and the precision lighting only on this runway seemed to indicate it was the preferred runway.) We were just switched to CTAF from Center and I heard the pilot not flying (Co-pilot) making the applicable traffic calls. As I turned onto final; I saw the lights at the airport were either not bright enough or not up at all; so I asked the Co-pilot to click on the lights. (I thought he'd done so earlier; but wasn't sure.) He did so; and made another call on CTAF to announce our arrival. As we got closer to the runway; we saw a light approaching from the opposite runway. I first thought it could be a helicopter maneuvering in the airport area (sometimes they don't talk a lot when training in low areas); but as I continued; the light appeared to maintain centerline and continue toward the opposite runway. I then asked the pilot not flying/Co-pilot to confirm we were on CTAF; as I initiated a go-around. He looked down and noted the frequency was set one digit off. After quickly tuning the correct frequency; the pilot not flying made a call that was received with a response that the other white-light-now-identified-as-an-aircraft was breaking off their approach. They then asked if we had been making radio calls. The pilot not flying said we had; but stated we realized we had incorrectly tuned one digit off when we saw their lights and got no response from our calls. We apologized and both aircraft landed uneventfully .What lulled me/us into a false sense of security was the pilot not flying was making all the right calls; and the runway lights even came on when he clicked on the CTAF frequency. Of course; that was coincidental; the other aircraft had clicked-up the lights at the same time! Yes; a mistake was made. Yes; the 'Mark I eyeball' (i.e.; looking outside) still has a place in aviation.