This is because there isn’t enough power being supplied to the BRIDGE CAST from the iPad/iPhone. Connect a commercially available USB AC adaptor (at least 5 V/1.0 A) into the 5V port.
* Before connecting the USB AC adaptor to the 5V port, set the USB connection setting switch to “CONSOLE/MOBILE”.
* Also, see the related Q&A, “When I unplug the USB AC adaptor, the BRIDGE CAST or iPhone/iPad sometimes becomes unstable”.