Black lines in background

I am attempting to use a set of huge prims to create a giant background for an island so that it looks like it is in the middle of a city. I have the skyline cut out on 256x256 textures that line up perfectly, and an alpha channel so that you can see the sky beyond the buildings. It looks pretty good, but I am getting black lines along the edges of each huge prim. The texture on each side not facing inward is a fully transparent texture. Please let me know why the black lines are coming up and how I can avoid it.

Thanks Much

Try setting the repeats to 0.98 or something similar, instead of 1.0.

SL tries to tile everything - even stuff set to one repeat. So if one edge is dark and the other is transparent, it may "wrap" a one-pixel dark line from the opaque side to the transparent side of the face.

Thanks a lot Ceera, that did it. The offset is a little greater than I would like, however. Its too bad that SL just rounds up the .00x digit or else I could get greater precision.