How to insert dynamic approval on sc_request table using script Servicenow

var approval_group = new GlideRecord("sysapproval_group");
                    approval_group.initialize();
                    approval_group.approval = "requested";
                    approval_group.assignment_group = 'f28af205db8225105db21232343sdf54';//  sys_id of group
                    approval_group.source_table = 'sc_request';
                    approval_group.parent = current.request;
                    //approval_gr.setWorkflow(false);
                    approval_group.insert();