Cant back up my iPhone

Im connecting my iPhone 6+ via the original lightning cable to the usb C/usb adaptor to my macbook. When i try to do a backup, it will always show iPhone is disconnected.

I'm guessing the problem is because now i'm no longer plug in directly to the mac via the lightning cable. Instead i have to use a usb C/usb adaptor. I have no problem doing similar task with my old mac book air.

Anyone has similar issue? i have tried all the method suggested online with regard to this problem.(These solutions were offered before we had USB C and the need to use an adaptor to connect the iPhone to the macbook)

am i suppose to wait for a usb C to lightning cable?