Why don't guys respond to me properly? I'm told I have a great personality and looks so whats wrong?

This isn't just one of those questions to seek attention. Seriously, I see them stare and we talk flirt smile etc etc etc. But when they don't make a move and I take the initiative (like casually ask them for a drink) they just don't reply. Or take ages to. Like I msged this guy 2 days ago and he still hasn't replied. Please help me to understand it is so bizarre! Mature answers would help