Unable to Extrude a Plane Whenever I add an Object or import an SVG object, I am able to extrude it either by E or by the extrude tool in object data, but I can't do that for a plane ( and just saw for a cube as well ). I get no options for it in the Object Data section nor does Pressing E Extrude it.
What have I done wrong or not installed?
In order to edit an object, you must be in Edit mode.

You can set the mode in 3D view > Header, or by pressing &#8633; Tab: