Mux16's 'sel' input is a single bit, not a bus. You should be seeing an error message in the status bar at the bottom of the simulator's window. (On some systems this can be hiddin with the default window placement. Move the window until you can see the bottom.)
Another way to see the error messages is to run the simulator from the command line:
% HardwareSimulator Mux16.tst
In HDL file D:\TECS\projects\01\test\Mux16.hdl, Line 7, sel: the specified sub bus is not in the bus range: load Mux16.hdl
When you have solved your problem, please edit your post to remov the HDL.