I don't know if this is the right place for this problem but here goes. I've just put a set of black nylon strings onto my Spectorcore fretless. A, D, and G strings sound fine through the piezo pup but the E string has a marked drop in volume. Strange thing is when I put my finger on the string over the piezo it returns to normal. Sound is fine through the mag pup. Tried putting the old half wound E back on and no problem. It sounds to me like the nylon string is not conecting with the piezo properly. Any ideas would be welcome.