The Phrase, "Tie a Knot"

Wrong. You can't tie a knot. It's impossible.

If it's not tied yet, there's no knot to tie. You have tie something, and in so doing create the knot. The knot is the end product of having tied something. By the time you've got the knot, it's already been tied. You can't tie it again - that would involve trying to make a knot out of a knot.

The phrase "getting tied up in knots" makes sense, though. It also might be relevant to you right now.