I have one of these in a completely rubbish 1970s variety that flowers for one week in the summer. Unfortunately, it is almost ALWAYS the week that I am away. So I have never actually seen it deliver. It is coming out this winter! So my first bit of thinking is: are you absolutely certain it hasn't flowered because with some of them, you blink and you miss it! 
They are really tough so will take a hard prune and pretty harsh living conditions too - most of them don't need a fussing. They tend to like being in the soil more than being in a pot as well.