iSunnao BC09 Wireless FM Transmitter

I guess it’s true you get what you pay for. Bought this on Tuesday night got it Saturday then I plugged it into my car cigarette lighter 3-way multi socket and it only works if nothing else is powered on. so then I plugged it in by itself to the car cigarette lighter socket and tried to plug something else into the socket the transmitter has and it won’t work unless its the only thing powered on.