Can not load the .bt map in octomap_mapping.launch.xml

[ZihuiGao]

I have add the args in the launch file like this:

<launch>
	<node pkg="octomap_server" exec="octomap_server_node" name="octomap_server" args="/home/ws2/ros2_ws/m.bt">
		<param name="resolution" value="0.05" />

		<!-- fixed map frame (set to 'map' if SLAM or localization running!) -->
		<param name="frame_id" value="map" />

		<!-- maximum range to integrate (speedup!) -->
		<param name="sensor_model.max_range" value="5.0" />

		<!-- data source to integrate (PointCloud2) -->
		<remap from="cloud_in" to="/points2" />
		<!-- <remap from="cloud_in" to="/scan_matched_points2" /> -->

		<param name="point_cloud_max_z" value="3.5" />
    	        <param name="point_cloud_min_z" value="0.1" />
	</node>
</launch>

But when I use ros2 launch octomap_server octomap_tracking_server.launch.xml, it will not load this map but generate a new map.
And the log is like below:
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [tracking_octomap_server_node-1]: process started with pid [97493]
[tracking_octomap_server_node-1] [INFO] [1714967965.560024868] [octomap_talker]: Publishing latched (single publish will take longer, all topics are prepared)
[tracking_octomap_server_node-1] [WARN] [1714967965.565592711] [octomap_talker]: Nothing to publish, octree is empty
[tracking_octomap_server_node-1] [WARN] [1714967965.565630448] [octomap_talker]: Could not open file
[tracking_octomap_server_node-1] [WARN] [1714967965.565642249] [octomap_talker]: Nothing to publish, octree is empty
[tracking_octomap_server_node-1] [WARN] [1714967965.565659940] [octomap_talker]: Nothing to publish, octree is empty
[tracking_octomap_server_node-1] [WARN] [1714967965.565675411] [octomap_talker]: Nothing to publish, octree is empty
[tracking_octomap_server_node-1] [WARN] [1714967965.565687955] [octomap_talker]: Nothing to publish, octree is empty
[tracking_octomap_server_node-1] [WARN] [1714967965.565702637] [octomap_talker]: Nothing to publish, octree is empty
[tracking_octomap_server_node-1] [INFO] [1714967965.565712257] [octomap_talker]: starting server

I always see "Nothing to publish, octree is empty" and "Could not open file" before and after I add the "args="/home/ws2/ros2_ws/m.bt".
How to load .bt map?