My 6yo daughter still wets her bed every evening. she is potty trained during the day. is this normal for a 6yo to use diapers at night?

No: If she has never achieved bladder control since birth (primary enuresis), she may respond well to ddavp(urine concentrating hormone) therapy. In case of poor response, alarm device attachable to underwear would be next treatment option which provides higher success rate. If bedwetting is a new event to her, a number of things have to be checked out, e.g., diabetes, bladder infection, etc.