I have made the first step on postgresql, but got some problems

few days before, I said I wanto joinin the postgresql develope group. and recently, I make some progress, such as get throught the base steps. but when i add some functions to the spatial data, such as box_add1() to box data, but when I compile it, and install it to my computer, it turns out ,the box_add1() didnot work, but the original one box_add(),which has existed in the current one, works. so what happened? and I check it, that, the declaration of the function, I add, can be found in the installed include files, it's local\pgsql\include\server\utils\geo_decls.h.

anyone can give me some suggestions? thankyou!