Fisher randomly standing and sitting back down

I haven't touched fisher in a while so today I thought I would go back to it, and I don't know why but they just keep randomly standing up and sitting back down after I make a cast. This is usually followed by a "Nothing bites" message. I've never had this problem before, and I don't really know how to fix it.

Sounds like you're using the wrong bait or you're underleveled for that spot.

Yea, if "nothing bites" it means that you're not using the right bait, or mooching something that doesn't actually have a fish that can bite with it.