Can't add fracture projectile - Beginner in need of help

So I’m a beginner when it comes to Blender, as may or may not be obvious when reading my question.

I was experimenting with the fracture tool and set up a fracturing sphere, which went as it should.
However, when trying to add a bomb or fracture projectile, it wouldn’t let me, telling me ‘Calling operator “bpy.ops.wm.link_append” error, could not be found’.
I’m using Blender 2.74

Is there anything else I should download or can this be easily fixed and am I just being dumb?

Any help would be appreciated.

If there is anyone who could explain how to turn an already existing mesh into a projectile, it would extra helpful, but it’s not the main issue of course.