Every stinkin' night!

Every night little Preston screams after he's put to bed. Whether he wants a drink *which he gets before bed EVERY night* or just to see someone, it is every night! it's maddening and really old. He's done this as long as he's been alive, which means we're not doing something we should be. Any ideas?? His reasons for crying are usually really lame, like, "I want my other pajama pants!" when he normally does not give a darn about what he's wearing, it's just an excuse. any suggestions? please? for our sanity? lol.