It seems to me like the gals speak two languages: "galspeak" and English (or whatever your mother tongue is).
A gal wants to communicate interest to a guy, and naturally, she uses galspeak. Her friends totally understand, but when it isn't understood/received/reciprocated by the guy, they blame the guy. Guys look at them, smile politely, and go on with their business, just like they do with foreigners. Gals read "Smile! Oh that's good!" (or whatever the appropriate translation into galspeak). They continue to use galspeak in communicating with the guy, and they continue to get polite (if increasingly perplexed) smiles. The gal continues to read "More smiles... good, and getting better!", and then they try to be overt, still in galspeak. By now the guy is really confused, if not creeped out, because at no time has he received anything which means approximately, "Hello! I find you attractive and I'd like to get to know you better."
So, maybe next time, try saying (or writing), "Hello! I find you attractive, and I'd like to get to know you better." Just.like.that.
And if he's not interested? Well, that's a possibility, and it might cause the introduction into galspeak of the concept of "Rejection hurts enough by itself... be gentle next time you give it."
Just a thought or two, from a guy who once received a bouquet of flowers on his desk at work (about 20 years ago), and to this day has absolutely no idea who sent them. Anonymous overt expressions of interest work almost as well as galspeak.