SQL & PL/SQL

I am trying to issue an UPDATE statement in a procedure in a package.

I use DBMS_OUTPUT.PUT_LINE to list all of the values Im trying to set.

My update statement looks like:
UPDATE table_name
SET ack_dtg = to_date(v_ack_datetime,'DD-MON-YY HH24:MI:SS'),
ack_error_code = v_err,
latest_dtg = SYSDATE,
latest_status_id = v_status_id,
original_dtg = v_time,
sent_count = v_count + 1
WHERE message_id = v_id;

All the variables on the right side of the equal sign have values that I can see using DBMS_OUTPUT.PUT_LINE.

I get and error that says:
ORA-01403: no data found
ORA-06512: at "SAMS.SI_TMIP_ACK_LIB", line 101
ORA-01403: no data found
ORA-06512: at line 1

I know its the input statement because my call to show the variable values is just before the UPDATE statement. Then I have an output statement right after the UPDATE statement that is not shown.

Any suggestions?