husband not bonding with baby

My husband has a 6 year old & we have a 4 month old together. He SPOILES his 6 year old and pays so much attention to her. If she doesn't get her way she wines & cries. But, when our 4 month old cries he ignores her. I feed her, change her diapers, play with her & rock her to sleep...I do EVERYTHING. Anyone else have this problem? I just feel like my baby is getting cheated :/