Q: New Magic Keyboard will not operate with Bluetooth

On the Bluetooth system preference page, my magic keyboard reads:  "Connected, charged."  I plugged it in to charge it, because the new iMac would not recognize the keyboard, even though I'm pretty sure it was already fully charged.  I had previously checked this system preference within the past hour.  If I disconnect the charging cord, the Bluetooth preference then reads:  "Not Connected."  It no longer serves as a wireless keyboard.