Yeah, I had this issue with my SL2 on my Soloist. I even have one of the outdoor heavy duty antennas. I could plug that same antenna into the boombox and get a full signal, into the Soloist with the Stiletto docked, antenna not detected.
By the way to answer Jamie's question from my experience the Stiletto showed ZERO bars of signal. Then one day out of the blue, I hooked up a regular home antenna and stuck it in my window, plugged it in and low and behold I got a signal. I never understood what it was about that big home antenna that it didn't like, but it didn't. Eventually though the regular home antenna started doing the same thing, no antenna connected! Go Figure!
Something is screwy with these Soloist docks.