Pixhawk 2.4.8 with Here+ v2

Hello Evereyone
Hy Its about two weeks I am stuck with my here+ rtk . Actually I want to use external Barometer on my pixhawk2.4.8 .My problem is when I change the hardware switch to CAN mode my external compass is unable to detect,even no sign of barometer. I also saw whenever I cange the hardware switch to from I2C to CAN mode a bluish low rate blink starts. I am using new firmware 4.0.3