Sometimes us guys are just a little bit slow on the uptake (not realizing you're interested in us), or are too shy to talk to as great a girl as you are.
Unless you live in a culture where a girl is looked down upon for making the first move, by all means, let the guy you like know that you like him. And make it very clear. You don't want any misunderstandings, right?
Even though I'm a guy, I'll admit we are often so focused on what's going on in our heads that we miss what is right in front of us. So you kinda gotta get a little blunt sometimes, just to get our attention.
So, go with whatever approach you're the most comfortable with, and if doesn't seem to be getting you the results you figure it should, you may need to try a little more direct approach.
Some people think that girls also should also have to make the first move. Basically if you are both shy, one of you will have to pluck up the courage to make the first move. It is not always better to let the guy make the first move, sometime they really like it if girls take the lead. If you will not do something, you might wait forever. Boys are also shy (though it is not really obvious) you shouldn't stereotype that guys must always make the first move.