ORA-04091

I am getting the following error . what changes should I made to avoid error?

 SQL> create or replace trigger insert_on_alarmlogtemp
  2  after insert
  3  on alarmlogtemp
  4  for each row
  5  declare
  6  v_alarm_id varchar2(255);
  7  v_alarm_node varchar2(255);
  8  v_alarm_dtm  timestamp;
  9  v_alarm_node_dtm varchar2(255);
 10  v_alarm_dtm_node varchar2(255);
 11  v_alarm_name varchar2(255);
 12  v_alarm_desc varchar2(255);
 13  v_alarm_status varchar2(255);
 14  v_created_dtm timestamp;
 15    begin
 16   select alarm_id,alarm_node||alarm_dtm,alarm_node||alarm_dtm,alarm_dtm,alar
m_node,alarm_name,alarm_desc,alarm_status,created_dtm
 17  into v_alarm_id,v_alarm_node,v_alarm_dtm,v_alarm_node_dtm,v_alarm_dtm_node,