Custom Skin Replaced By Default

I Uploaded a skin and I logged in,
launched the Game Then I Went In!
And I Expected that my Skin Would Show...

...But Instead It Was The Default skin.
I Tried Uploading it again but It Didn't Work'
I Tried EveryThing! But It Failed. :,(
Describe what happened here

Steps to Reproduce:
0.5. Upload a Skin (Optinal)
1. Go To Version 1.7.7 or 1.7.6
2.Launch game And go To Multiplayer or Realms
3.Viola! Your Skin Is A STEVE skin!!!!
(For some People It Does Not work)
3. ...