It could have multiple sources, two of them I could think of at the moment is that you have:

 - more than one material in the Material Slots, and you're editing one that is not assigned
 - more than one UV Map on the object, and the one which is currently renderable is empty

To check the material assignment, you can use the Material Tab like this:

[![multi Material][1]][1]

To check the UV Maps, you can use the Mesh Data Tab, UV Maps section:

[![multi UV][2]][2]

Regarding the UV map, the one with the camera icon behind is the one that is sent down the material tree when you plug the UV output socket somewhere. To choose a different UV Map you can use the dedicated UV Map node:

[![UV chooser][3]][3] 


  [1]: https://i.sstatic.net/pFfDa.gif
  [2]: https://i.sstatic.net/42nry.gif
  [3]: https://i.sstatic.net/9Ioqo.gif