Check and make sure that the addons are in the following file path:
(Assumes you installed WoW defualtly)
C:\Program Files\World of Warcraft\Interface\AddOns
The most common reason for the addon button not to show up is that the addons were not unzipped into the correct folder.
Different UI authors use different zipping convientions so have you unzip into the addon folder others the WoW root folder.
So just check and make sure the add ons are in the right place.