I'm having a problem with building walls - some of my walls are suspend before they can be built. The suspension message is that there's a creature occupying the site. I've been watching and a dwarf will enter the space that the wall is to be built in, stand there for a while, I'd assume trying to build the wall, and then suspend the construction... so I think the builders themselves are the creatures in the way of building? Is that possible? How do I fix that?
Here's the layout:
X = built wall 0 = unbuilt problem wall ~ = water tile _ = empty dirt tile ~_____________ ~0__XXXX0XXXXX ~X____________ ~X____________