Why might I find it hard to day dream about my stories?

I love day dreaming and I love writing. It seems I can't mix the two though. When I try day dreaming about the events of my story, I can't. It's like I get bored with it even though I love the story idea and everything. Right now, I have my stories planned out with each event being bullet pointed on Word. I've started writing the beginnings of them too. So I know it's not because I don't know what should happen. What might be the problem?