I had the same thing happen a couple weeks ago. After the third pass without a bite, I pulled 3 of my 8 rods out of the water and went back with 5 rods set for vertical. I set two rods on the bottom, 2 about 5-8' below the surface and one in the middle of the water column. I ended up catching a few more, and all of them came on the baits that were on the bottom.