It sounds to me like you might have used the Curse updater, or allowed the Curse updater to automatically update nUI. You cannot do that as the Curse updater will overwrite the nUI+ version with the nUI (Lite) version.
You can tell which version is loading by looking at the welcome message that prints in the chat frame when you log in. If it does not say nUI+ 5.07.10 then you have the wrong version.
What people don't get is that I am, ultimately, an artist at heart. My brush has two colors, 1 and 0, and my canvas is made of silicon.