type Sequence struct

{     Id       primitive.ObjectID `json:"id"   form:"id"  bson:"_id"`     Field    string             `json:"field" form:"field" bson:"field"`     Sequence int64              `json:"sequence" form:"sequence" bson:"sequence"` }

 
func (model *Sequence) GetNextSequence(field string) (int64, error)

{     err := util.C(model).FindOneAndUpdate(context.TODO(),         bson.M\{"field": "Account.Number"}

, bson.M{"$inc": bson.M{"sequence": 1}},
        options.FindOneAndUpdate().SetUpsert(true)).Decode(&model)
    if err != nil

{         return -1, err     }

    return model.Sequence, nil
}
The first run func,can get correct result.Continue to run func  ,but not inc, still the first result. What is the right thing to do？
Thanks。