"No heartbeat packets received"

hi, i use arducopter autopilot many time but i’m new in modifying its firmware and building it.

I have downloaded the code as described in “where to get the code” and i have built and loaded the firmware as described in “building Ardupilot with Arduino”. This step seems to be completed successfully but when i try to connect the APM with mission planner i got the message “no heartbeat packets received” after mavlink connection timeout.

Thinking at an hardware problem i tried to load arducopter firmware via mission planner and in this case everything goes well.

I haven’t done any modification to the source code

could any of you help me?

thank you

just a mistake in my sentence…i have modified only APM_config in order to select the desired frame and remove AUTOTUNE function, otherwise the total size exceeded the maximum