What you've written here is a little hard to follow - are you trying to say that if your sim is trying to fish and you click on open water, it works, but if you click on the spot where you see fish swimming, your sim doesn't do anything?
This sounds like an old bug that was fixed in a previous patch - do you have the most up-to-date patch installed?
Did it just start recently? Or has it been going on for a while?