simulation problems:Warning: (vsim-3473) Component instance "i1 : ex1" is not bound.

Modelsim needs to compile all the components in your design. This message means that you have not told Modelsim to compile the component ex1.

Your filename looks a little weird, is ex1.vht supposed to be your testbench file? A more normal convention would be the component source is ex1.vhd and the testbench source is ex1_tb.vhd.

But since you said that your top-level design was a schematic, perhaps that it just what Quartus generates. In that case, you may have a problem with your top-level design being called ex1, and your component being called ex1. If that is the case, change your schematic name to ex1_top.

Cheers,

Dave