Thank you all for the great replies!
Sean, I haven't really tried to use a voice, so it's not that I'm trying too hard. Maybe the problem is that I'm not trying at all. I think I'm afraid that if I try to use my voice, it's going to sound too conversational-- too full of "suddenlys" and "and thens".
Sunna, I feel pretty good about my pov characters, so I don't think that's the problem. At least not in this particular story that I'm working on.
Mumut, no it's not just a voice telling the story. I do have dialogue. And you're absolutely right about conversation picking up a flat piece of writing. I think my writing is crisp and to the point, maybe too crisp and too the point and devoid of personality.
Linnea, I'm so focused on finding the perfect word, making sure the dialogue is realistic, eliminating adverbs and repeat words, using commas correctly, and creating vivid scenes, that I think I've squeezed the life out of my storytelling voice.
Thanks again, everyone. Please keep the advice coming.
(I love this place!)