My ciabatta dough hasn't risen after 2 hours! I mixed my ciabatta dough 2 hours ago, and it's barely risen at all.

I put it in a greased plastic container in the hot water cupboard, and marked the level to know when it "tripled in volume". The hot water cupboard isn't particularly warm, but it's not cold. The container is a tall storage container (it used to hold flour), and I had put the air-tight lid on lightly which the dough has opened (with air pressure).

I made a biga last night, which had fermented for about 6 hours before I put it in the fridge. I made the ciabatta dough with biga, high-grade flour (although recipe called for AP flour), yeast (1 tsp), salt, cold water. No sugar. I mixed it with a food processor.

Sorry about all the details, I don't want to miss out anything that might be a silly mistake. Is there any obvious reason it's not risen? 

(I can provide more details about the recipe if that helps...)

Edit: I just touched the dough and its pretty cold, so no wonder its not rising! I guess it would have been a good idea to "wake up" the biga before mixing the dough? Any suggestions how to proceed from here?
As it turns out, my dough was very cold. Due dilligence: here's a full answer.

One of the requirements of yeast for fermentation is appropriate temperature. Cold dough straight from the fridge won't rise, or it will only rise very slowly. 25-30°C is a recommended temperature range for rising, although cooler temperatures can work.

Duh.