There are three logos for the template, each named for the color. An easy way to find out the name and location of the logos, is to unzip it to your desk top and look in the image folder for the name. Also check to make sure you use the same file extention and spelling.
Example: if the extention is .png dont use .PNG same with .jpg not .JPEG or JPG
Also after you change your logo make sure to clean your browser cache. Heres a link on how to clear the cache folder. http://kb.iu.edu/data/ahic.html