Which line of code gives the error

I've got a problem thats driving me nuts. I've got a procedure thats failing with the following error:

declare
*
ERROR at line 1:
ORA-01861: literal does not match format string
ORA-06512: at line 83


Line no 83 of my code is the end of the following cursor:

for r_mpan in c_mpan loop
concat_mpan := r_mpan.mpan_rec||r_mpan.mpan_ref1||r_mpan.mpan_ref2||r_mpan.mpan_ref3;
Insert into esales.mpan (mpan_id)
values (concat_mpan); <<<<----------- LINE 83

My question is - is it this loop thats causing the problem or is the error caused by the next loop? I'm 99.99% sure this loop is OK - the concat_mpan variable is a VARCHAR2(13) and all the rows returned by the cursor are 13 characters long.

Any help would be appreciated as I'm about to tear my hair out!!!

Are all the columns you are concatinating VARCHAR or CHAR fields? Also what are the sizes attributed to the columns?

Regards

the four columns are varchar2(10)'s but when concatenated they are only 13 characters long. Also the column in the insert statement is a VARCHAR2(13). I've tried changing all the VARCHAR2(13)'s to VARCHAR2(40)'s but am getting the same error.

This error is related to conversion functions.
In case you use to_date or to_number functions with format string somewhere around line 83, focus on it.