In Poser 6 load the figure from the character library. Then go to the pose library. Select the MAT file specific to the character you are using and click the checkmark at the bottom of the library list. Make sure you have the character selected before trying to apply the MAT pose and not a prop or other object. Make sure the texture is intended for that character. V2 textures won't work on V3, one type of clothing item texture won't wok on another.