Unit with Bridge Model

I am making a map and I want you to be able to walk underbridges. I know this has be discussed many times and I know how to do it. I am trying to make a flying unit with a bridge model. This only seems to work for some bridge models and im not sure why. The Long Natural Bridge for example comes up all white. While the Long Wooden Bridge works fine. Why is this and how do I fix it.

because of the texture pathing, instead of having 8 of the same bridge models, blizzard made it so that 1 bridge model uses 8 different skins, depending on the terrain, i think all you need to do is set the texture pathing...

(havent used we in a long time, so im not sure)

Psht, don't use a unit, just use a doodad with no pathing map, then set it's height.

Im working with a unit using a bridge model, I cant change the pathing texture. I may need to make a custom model with the texture allready set but im not sure.

And I cant use a doodad with no pathing because the unit still appears to walk above the bridge and not under it. As far as I know the only things you can walk under are flying units.

Uhh, you can make doodads you can walk under. You just have to make sure that you didnt base the doodad off anything in the ramp category.