Building Corps (White Giant)

I have had a couple of requests to build corporations in my country of United Wealth which I have accepted, as well as some requests to transfer corps to my country that I have accepted. However it has been several game months now and only the relocation requests have worked, none of the build requests have started building a corporation and its been many game months, it says that construction will only start if I have enough Building Capacity, what is this and how do I make sure I have enough. Any ideas on how to solve this problem and get these corps build will be greatly appreiated thank you. tomtalking@hotmail.com.