Oncidium refuses to flower
 

I have had an oncidium for three years ( I don't remember the name). It has at least 10 large psuedo bulbs, gets direct sun for two-three hours in the AM, dappled shade the remainder of the day. (It grows in the same environment as my catts and they blossom in season.) Leaves are light green. Fertilize weekly, 1/4 strength 20-20-20.
It puts out new bulbs but no flowers. I am growing it in Atlanta.
Any advice to get it to flower?