I told you, set the location to CATHERBY. Otherwise it will go to the fishing spot you selected. If I choose herring and set the location to Lumbridge or Mudskipper point for example, it will start running away up the white wolf mountain and whatnot.
There is the script working perfectly fine at catherby. If you still have issues, open the console log and tell me what 'My Spot set to []' says. Although this should fix your 'errors'.
My best guess is that you aren't even changing the location of the fish at all, and it is walking all the way to lumbridge - as I have just tried that myself and it did indeed start walking north. Just set it to catherby.