It's quite easy to slip into concentrating on playing what the tab says, and not manging to get it to match the music .I finish up like that sometimes, and I've found that what is needed is to listen to the bassline as a melody and hear the tune, and become familiar with it. When you know what you're trying to get to as a musical piece rather than a series of numbers on a page, it's easier to get there. I probably haven't expressed this very well, I know what I'm trying to say but I don't know whether I've conveyed it well.