This is really strange. I can't connect my new Tab S 10.5 to my imac with the usb cable. I've replaced the cable and power brick but to no avail. When I connect the device to the power, there's a small red "x" on the battery icon and no charge is going on. But when I use the same cable and charger on my S5 it works, charges and connects to my imac. What am I doing wrong with the tab s?