Why do some of my skins show up completely invisable?

[Cold-Voice]

For some reason, when I apply certain skins on to the units, the unit goes completely invisable, except for the team colour. Whats the problem? I am using PSP v.9 if it helps anyone to figure out what the issue is.

 

[Saikann]

its the alpha channel that's gone corrupt

 

[Sopho]

Read my corrupted alpha channel tutorial.

 

[Cold-Voice]

Ah, thank you both. That helps alot.