The problem I had is bit 0 of the status register is stuck at 1 (reset), and according the user's manual, this bit has to be set to 0 to be able to operate the switches. I wrote to this register to set this bit 0 to 0, but when I read it back, it's still 1. I can set/reset other bits of this register but not bit 0. I don't know why. Your help would be profoundly appreciated.