When i run (roslaunch moveit_gui_all.launch)..its saying [moveit_gui_all.launch] is not a launch file name .What is the problem??

Hello I am new to ROS so i don't know whether i am making a silly mistake or not. When i run (roslaunch moveit_gui_all.launch)..its saying [moveit_gui_all.launch] is not a launch file name The traceback for the exception was written to the log file .I have installed moveit properly..Please help