Did you try the top with the key in no.2 position in the switch. mine used to operate with the engine running in park and now only with the key in no.2 position, I did a search on the SL forum about this problem and there is a lot of info about this issue, there is one thing that everybody agrees on, the top will not work if the windows are not sync. hopefully is something simple like low fluid in the reservoir, I had that before.
good luck