Help! My baby is being difficult

My 7 month old daughter will not go to sleep without being cuddled or rocked. She sleeps in her crib but won't soothe herself to sleep in it. But she will everywhere else. My bed, the couch, a swing, everywhere but her crib she will put herself to sleep! I've tried rocking her until she's just drowsy and as soon as I lay her down she wakes up and is wide awake all of a sudden. I've tried just leaving her in there and she doesn't cry at all but she just crawls around and plays with her feet (lol). I don't know what to do!!