Oh, you spit on the line.....thought you just spit for good luck and if the knot is in the way, oh well, it gets washed off anyhow! :D .
All my lures get tied the same way, for freshwater anyway. My knots do knot (sorry) come loose. Try this.
Pass line [call it A] through eye, and returns [tag line is now called B]. Send line [now on return is called C] back to eye forming a loop, but do not go through the eye. Hold lines A and B together and wrap line C around them six times, spit for good luck and pull knot together. Will not come apart.