I'll need to check into this with my own PoserPro since it has been awhile since I actually needed to create a MAT Pose.  In the meantime, just make sure that 'Body' of your clothing is selected before applying your texture.

Edit:  Okay, I just checked the saving settings for the Material Room for new material.  Upon clicking the '+' in the library palette, you should get a new window for naming your new material set.  Make certain that you select 'material collection', then click 'material selection'.  A new window will open with all the material sections selected for your clothing.  Deselect those you don't need  and click ok.  Click ok again to create your material.  And that should do it.