Trigger fails when variable used in WHERE statement

Question

I have a trigger that works when the following statment is in it:
SELECT custcall.callrkey into v_callrkey from custcall where custcall.servno = 152345;
But the trigger fails when I attempt to use a variable in the where statement as follows.
SELECT custcall.callrkey into v_callrkey from custcall where custcall.servno = :new.servno ;
Even though I have verified that the value of :new.servno is set to 152345 by outputting the value . That is the only difference between the working version and the non-working version. By not working I mean that the email which is to be sent by the trigger is not received.
Can anyone give me any ideas of how I could troubleshoot this or what might me happening? I'm pretty new to this and
feel that I'm missing something very simple. My apologies in advance if this has been posted elsewhere. I did spend a lot of time searching the forum before posting.
This is Oracle 9i.
Thanks!
Full code probably not necessary but posted below just in case:
create or replace
TRIGGER EMAILNOTIFY_NEW_SR
AFTER INSERT ON CUSTPROB
FOR EACH ROW
DECLARE
--SMTP Variables
vreply utl_smtp.reply;
vreplies utl_smtp.replies;
mailCONN utl_smtp.connection;
mailHOST VARCHAR2(64) ;
--MESSAGE Variables
mailText VARCHAR2(64);
mailFROM VARCHAR2(64);
mailTO VARCHAR2(64);
mailDATE VARCHAR2(20);
v_servno number ;
v_callrkey number ;
--PROGRAM Variables
i number;
BEGIN
--get some values from the database  
--set values for variables...
mailHOST:= '10.35.173.15'; --this will always stay the same 
mailFROM := 'Facilities_Customer_Service_Center'; --this will always stay the same
mailTO := '[email protected]';
SELECT custcall.callrkey into v_callrkey from custcall where custcall.servno = :new.servno  ;
SELECT TO_CHAR(SYSDATE,'MM/DD/YYYY HH24:MI:SS') INTO mailDATE FROM dual;
dbms_output.put_line('open_connection');
dbms_output.put_line('---------------');
vreply := utl_smtp.open_connection(mailHOST, 25, mailCONN);
dbms_output.put_line('helo');
dbms_output.put_line('----');
vreply := utl_smtp.helo(mailCONN, mailHOST);
dbms_output.put_line( 'code = ' || vreply.code );
dbms_output.put_line( 'text = ' || vreply.text );
dbms_output.put_line('mail');
dbms_output.put_line('----');
vreply := utl_smtp.mail(mailCONN, mailFROM);
dbms_output.put_line( 'code = ' || vreply.code );
dbms_output.put_line( 'text = ' || vreply.text );
dbms_output.put_line('rcpt to');
dbms_output.put_line('----');
vreply := utl_smtp.rcpt(mailCONN, mailTO);
dbms_output.put_line( 'code = ' || vreply.code );
dbms_output.put_line( 'text = ' || vreply.text );
dbms_output.put_line('open_data');
dbms_output.put_line('---------');
vreply := utl_smtp.open_data(mailCONN);
dbms_output.put_line( 'code = ' || vreply.code );
dbms_output.put_line( 'text = ' || vreply.text );
--SMTP ENVELOPE STUFF (In case it is needed later).  
--utl_smtp.write_data(mailCONN, 'From:'  ||mailFROM     || chr(13));
-- utl_smtp.write_data(mailCONN, 'To: '||mailTo || chr(13));
--utl_smtp.write_data(mailCONN, 'CC:      '||mailFROM     || chr(13));
--utl_smtp.write_data(mailCONN, 'Date:    '||mailDATE     || chr(13));
--utl_smtp.write_data(mailCONN, 'BCC:     '||mailFROM     || chr(13));
--THE MESSAGE
utl_smtp.write_data(mailCONN, 'Subject: '||'Your Facilities Service Request ' ||'(SR '||v_servno||')'|| chr(13));
utl_smtp.write_data(mailCONN, '');
utl_smtp.write_data(mailCONN, '');
utl_smtp.write_data(mailCONN, 'Dear Customer ' || chr(13));
utl_smtp.write_data(mailCONN, '');
utl_smtp.write_data(mailCONN, 'This is to inform you of something.' || ' ' ||mailTO|| chr(13) );
utl_smtp.write_data(mailCONN, 'Please call us with any questions or concerns. ' || '' || chr(13));
--DEBUG
utl_smtp.write_data(mailCONN, 'DEBUG: ' || ''|| chr(13));
utl_smtp.write_data(mailCONN, 'v_Servno ' || v_servno || chr(13));
utl_smtp.write_data(mailCONN, 'v_callrkey ' || v_callrkey || chr(13));
--END THE MESSAGE
dbms_output.put_line('close_data');
dbms_output.put_line('----------');
vreply := utl_smtp.close_data(mailCONN);
dbms_output.put_line( 'code = ' || vreply.code );
dbms_output.put_line( 'text = ' || vreply.text );
dbms_output.put_line('quit');
dbms_output.put_line('----');
vreply := utl_smtp.quit(mailCONN);
dbms_output.put_line( 'code = ' || vreply.code );
dbms_output.put_line( 'text = ' || vreply.text );
END;

Answer 1

Justin,
Thanks for the reply. I'm away for a couple of days but when I get back to this I'm going to follow up on your suggestion about servno. I'm starting to think that the issue isn't with servno but rather that the select query doesn't return anything because the value I'm trying to get is in another table and is not being inserted in time for me to get them. This will be easiy enough to test. To be honest, I don't know very much about how things are being inserted.
I appreciate your and Tubby's (and Tom's) concerns. Maybe I'll go back to the drawing board next week. But note that I'm not inserting anything with this trigger--only sending an email based on the insert that is happening through an application. So unless I'm really missing it, my email is dependent on the insert but not vice versa. Since my email is absolutely critical but rather jus a courtesy thing, I was taking a pretty laid back attitude about it but it would be good for me to learn a better way.
Thanks again to all! I'll report back what I find/decide.