{SOLVED} Shader issue (maybe?) with wall decoration

Hey guys. I've hit a little snag quite early on with this mod I'm working on, and I was hoping someone could give me a push in the right decoration. I've cloned an EA painting, and switched the mesh out for a plain flat box that's one-tile wide. I want to be able to place this mesh multiple times to create a continuous box along a wall, a bit like modular shelving. My problem is that it's not even sort of seamless. In almost every kind of lighting, it's really easy to see that I have multiple objects placed, rather than giving the illusion of being a single object like I was hoping.

Here's a screenshot:




See what I mean? Is there a way that I can fix this?

Tools I'm using are S4S 2.7.0.9 Jackpot, Blender 2.70a and Photoshop.  In case it's relevant: I've already updated my Shadow LODs and the shadow plane (used orangemittens' tutorial but it's possible I did it wrong, of course), and the normal and spec maps are blank. 

Thank you so so much in advance ♥