Issue regarding Obstacle Avoidance

Hello,

I am testing for Obstacle Detection with Lidars(1. forward-facing, 2.Downfacing). Up to Terrain following using Rangefinder is going good, after I Include forward-facing lidar for Detection of Obstacles. At this time I am facing an error message is “Err: Terrain-2”. What this error message
meaning.

IF I disable the OP_TYPE =0 Drone is flowing terrain, But OA_TYPE =1 the drone is losing its altitude. how to resolve this, please help me. Logfile is hear

Thanks and regards
Mohan