ERROR: cannot launch node of type [darknet_ros/darknet_ros]

[mazik1496]

I am currently using ubuntu 20.04 noetic and I am trying to use yolo using the camera in the gazebo environment I am studying, but when I run roslaunch darknet_ros yolo_v4.launch, the following error occurs.

So, I tried to enter the path and chmod +x, but there is no node file and only the package folder name of the same name exists. I thought I didn't do devel/setup.bash, but I'm very embarrassed because I've already done it several times and reinstalled the package several times. Does anyone know a solution for this????