Modeling glitch or ignorance?

[nexis]

I am new to modeling and have recently attempted with blender to make a simple wall for a static object similar to the walls in the editor ,but failed while checking to see if it would show up in the "ModelEditor".
Curious as to whether this is a fault of my own or a software issue.

Here is the List of steps;
I. Deleted cube and created a plane.
II. Highlighted single face of the plane and unwrapped UV.
III. Applied texture without issue.
IV. Exported as a COLLADA file into a folder outside of the Amnesia directory.
V. Terminated "Blender" and entered Hpl model editor.
VI. Imported Dae mesh.
VII No mesh was apparent so I selected the general area where it should be.
VIII. The mesh appeared; but only half of the plane existed (bifurcated diagonally).

Any help you could give is appreciated and if any detail you may need to diagnose this issue is missing post so I can revise.

Thank you...

[MrBigzy]

You have to triangulate the model; quad polygons aren't supported by the engine (at least in terms of texturing).