It's not a psychological problem. It's not because the child is too lazy to get out of bed to go to the bathroom. And children do not wet the bed on purpose, out of spite or to irritate their parents. In order to rule out medical problems, I recommend that your daughter be evaluated by your health care provider first. Although you may be worried about your child's bed-wetting, studies have shown that children who wet the bed are not more likely to be emotionally upset than other children.
Most children outgrow bed-wetting without treatment.
Behavior therapy is a treatment that doesn't use medicine. It's often tried before a child is given medicine. Examples of behavioral treatment are bed alarms, praise, dietary changes, etc. Medications are typically used after the child is seven years of age or older and if behavior therapy hasn't worked. Medicines aren't a cure for bed-wetting, they only control a symptom.