some basic reasons why an image might not display properly...or at all.
If its a bitmap...its not 24bit.
If its tga...not 32bit. Never get these backwards...dont save your tga's as 24 and dont save your bitmaps as 32.
If its a 24 bit bitmap...never check this image has an alpha channel...they dont,only 32bit images have alpha channels.
If your sizing margins overlap(like cross each other)...this can sometimes cause them to display incorrectly.
I see from the pic you checked transparent but the image dosnt APPEAR to be transparent(or translucent)IF an image is never transparent or translucent just use a bmp and uncheck those 2 options(trans and alpha)The reason I say this is bmp is always more stable than tga if your having problems with problem images...windowsXP just plain handles 24 bit images better than 32.
BUT...32bit images give you much more freedom in your skinning because of the alpha blending.(truthfully,they should rarely give you issues if your settings and bit depth are correct)
To avoid possible image corruption...do not let Skinstudio automatically convert images for you.If your image editor isnt handling the tga format properly...find a patch for it or use something else.
Skinstudio has many times corrupted images(almost unnoticeably but still degraded)during its tga saving and resaving.Plus your skin folder gets filled up with png's it created in the conversion.
The subframe builder is a cool feature but it degrades image quality with each save.
