Sounds like you have a parasitic oscillation going on; when you hit that spot on the dial, it's swamping the signal. Which kit did you build, did it provide a layout, and did you follow it? Can you post a schematic and any docs that came with it?
PS: keep only one thread open; first, it's bad forum manners to run three concurrent threads, and two, it keeps the flow of information & progress all in one spot. Thanks!