Model data not getting on server when hovering a call to backbone.js?

I am trying to save a model to the server from backbone.js. My problem is when I make a post call, all the model values ​​are received on the server successfully, but I am making a call on the server after setting the model id. It makes the call successfully, but I have not used the model values ​​on the server even though the model is populated with client side values. I am using follwing code. Please direct

        var isAdd = false;
            if (e.insuranceId != 0) {
                this.model.id = e.insuranceId;
                isAdd = false;
            } else
                isAdd = true;
            this.model.set('PatientId', this.options.patientId);

             this.model.save({}, {
                success: function (model, resp) {
                    console.log('success');
                    if(isAdd)
                    self.model.set(self.model.defaults);
                    self.insuranceId = model.attributes.PatientInsuranceId;;
                    self.saveFrontImageDB();
                    self.showConfirmation();
                }

            }