Every books has scenes in it where "nothing happens." No explosions, no dead bodies, no break-ups, no make-up, no make-out... no ninjas dropping from the ceiling.
Sometimes you need a scene just to get information across to the reader. This may be:
1) Clues to the mystery that don't seem important at the time, but will be vital later.
2) Character development.
3) Establishing the value of a place, situation, or relationship so that the reader knows how important it is before you, the author, either destroy it mercilessly, or put it in jeopardy.
The problem is, those are YOUR goals as the author. The reader doesn't care what YOU are trying to accomplish in the scene. He or she only cares what the character is trying to accomplish in the scene.
Even in ninja-less scenes, something *does* have to be at stake for your character. It doesn't have to be a BIG something, but it has to be A something.
Say your (author) goal is to have your knight in shining armor chat with the princess a bit so that when the princess is later kidnapped by the Evil Sorcerer, we will care that the knight gets her back.
He (Sir Dauntless) still needs a goal to give the chit chat tension. Does he like her and want to impress her? Does he want to NOT like her because she's off limits? Or maybe his goal has nothing to do with her: Does he just want to get through dinner without humiliating himself?
I wrote a scene recently where the heroine's only goal was to get from one side of the room to the other, but people kept interrupting her to tell her or ask her things--about her sister, about her mother, about a rumor going around town (that would, coincidentally, be extremely important in the next chapter).
My heroine wasn't trying to learn these things. She was just trying to get to the bathroom. But giving her a goal, ANY goal, gave the scene much needed tension.
Ideally, the reader didn't (wouldn't) notice what I did there. Half of what we do as writers is subliminal. She probably wouldn't notice if I just had my heroine wander around the room with people randomly stopping her to chat and drop nuggets of useful exposition in her lap. But side by side, one scene has energy, and one is obviously an excuse for me to exposition.
So add a little tension to your scenes by giving your character something to accomplish (or try to accomplish) in every scene.