Your question is exceptionally unclear. You have a single object selected, you do not offer any information as to how you are trying to align that single object nor any detail as to what exactly isn't working. However....
Align has three functions:
- Align to arbaord
- Align to other objects (selection)
- Align to a single key object
Items 2 and 3 require more than one object be selected before they function.
The only time you can use the align functions on a single object is when Align to artboard is selected as the alignment method.
Based on your screen shot, with only one object selected, I would guess that you do not have the options set to Align to Artboard.