My pole is highlighted in green when I try to fish. What am I doing wrong. It happened before but forgot what I did for it to work.

the fishing skill(in the general tab of your "spellbook and abilities") needs to be used to cast your line to initiate the fishing process, then you need to wait for the bob to move when a fish strikes then right click on the bob. (a cog should be visible when the mouse is over the bob) If your quick enough you will catch fish, happy fishing! if u equip the fishing pole and right click on a school of fish all you will do is beat them to death with your pole haha!