IndexError while Calibrating Bittle

Hi,

I have assembled the Bittle (with Nyboard V1_2 board) and ensured all servo circuits are connected to the motherboard, the battery is fully charged and Connect the USB adapter and communicate normally. As I have built the robot with an unassembled kit, do not install the head and leg components before attempting to calibrate.

I am calibrating the Bittle using Petoi Desktop App. When I run the UI.exe and click on calibrate, I am getting following error message;