kilboj

On my '99 500 SL, when I go to open the top, the back parts work fine, then nothing happens. The front top locks do not pop. Nada. At my local specialist, of course, the top worked fine, so I drove 40 minutes to get it, and it failed for me and the specialist both. The fluids are fine - when the top decides to work, it does so perfectly and as it always does. No leaks.I suspect an intermittent relay or switch or module. Any thoughts?

Thanks,

JK