Casting Shadows from 3D objects - FIX?

Hi,

I am new to 3D objects but I am pretty confident I have set this object up correctly. The issue is when I use infinite light, there is no shadow cast by the object. I have ticked 'cast shadow' on the object and played with intensity but I just cannot see it?

(I have extruded a 2 d object to create the 3d one if it matters?)

Any support is much appreciated.