I will sound like a broken record here, but post up a photo of the nub, etc... Also what are the cattleya crosses you are growing? Usually it is one of three things that cause orchids to not bloom. 1. water (too much or not enough) 2. light (too little) 3. Fertilizer (not balanced or delivered to infrequently). I am guessing that since your plants are growing and appear healthy that it is the LIGHT that is the problem. But, post up a photo so we can see what you are describing. I don't expect that you would even get buds if there was not enough light, but maybe that is the case.