E: Unable to locate package ros-melodic-realsense-camera

edit

recently, i try to set up realsense_camera

but when i try to ROS Debian Package install i got a error ( site : http://wiki.ros.org/realsense_camera ) like

E: Unable to locate package ros-melodic-realsense-camera

please, help me !!!

this is my all commend :

c@c:~$ sudo apt-get install ros-melodic-realsense-camera
Reading package lists... Done 
Building dependency tree       
Reading state information... Done
E: Unable to locate package ros-melodic-realsense-camera