New Building Question

When adding a new building how many (and what) pictures do you need?

I created a treasury building with one level small_treasury and have added the following pictures:

data\ui\culture\buildings\#culture_small_treasury.tga
data\ui\culture\buildings\#culture_small_treasury_constructed.tga
data\ui\culture\buildings\construction\#culture_small_treasury.tga

but when I run the rtw, in the list of buildable buildings I get the default no building found picture and an error in the exe on exiting (standard "rtw.exe has encountered and error" message from windows, no show_err message); however, if I add small_treasury forum to the descr_ui_buildings.txt file it shows the forum picture in buildable buildings list as the treasury and I get no error. The weird thing is I've unpacked the ui files and can't find any other forum picture other then the ones for which I have an equivalent small_treasury picture.

Any ideas on the problem would be appreciated.

EDIT: Problem solved misspelt the name of a folder