Silver Textures Appear where Mine Are?

[TheMightyFlakes]

Okay, so I'm having some trouble getting textures of mine to work in Brawl. The issue is that certain parts that have transparent textures would appear filled in before with a beige tone rather than being invisible. So i made those images indexed rather than rbg in GIMP and now they appear entirely silver and shiny. What gives, and how can I get the textures to apply themselves how they should? Note: I tried letting BrawlBox select the recommended format before replacing the images the second time? Should I do this, and what is the format type I should use? Thank you in advance for any help, and if need be I will upload the textures here.

[Gamma Ridley]

Please upload the original texture, it would probably help.