Why my Mac keep saying "Try reconnecting or restarting your device"?

[AC Question]

I want to transfer pictures from my S4 to my macbook. They said I just need to have the Android File Transfer downloaded on my mac. I've done that part but unfortunately every time I connect my S4 to the mac via USB cable, it keeps saying "Try reconnecting or restarting your device". I did restart my phone and even uninstalled the AFT then downloaded it back, still, the same problem keep happening.

What should i do?

 

[StevieRich]

I have a Galaxy A3 phone, running Android 5.0.2 and the same problem. Connecting the phone triggers the AFT software, but the connection doesn't really start: it keeps saying: "Try reconnecting or restarting your device".