Standing Seam PS hack for depth.

[jtcapa1]

Rene posted a cool Youtube video on how to stack a .png texture to generate the appearance of depth in 3d.

Works great, IF you have the right PNG setting.

I'm close on a making a exterior wall with vertical wooden slats, except I'm getting a light white line or reflection at each 40"x40" edge.

Any idea's what I'm doing wrong, or what I can do to the .png to avoid this artifact?