Check your Prepare Matrix Texture command.
Do you have a single texture for the whole matrix? If so, assuming it's matrix number 1 and uses image number 1 you need to use:
Prepare Matrix Texture 1,1,1,1
If you have more than one texture, then they have to be placed in a 2x2, 3x3 or 4x4 etc. grid and the grid size used in the Prepare Matrix Texture command:
Prepare Matrix Texture 1,1,2,2 ... or
Prepare Matrix Texture 1,1,3,3 ... and so on.
If you get stuck, check out the matrix tutorial on my web site (link in sig below).
TDK_Man