ora-06502

Hi all,
I have a PL/SQL procedure that reads data from a DB2 table across a database link using Oracle Gateway. The column causing me a problem is a CHAR(10) on the DB2 side. I am reading it and placing the data into an Oracle table where this column is defined as VARCHAR2(10).

If the data in the DB2 CHAR(10) column is like '1880 E', I get the following error when running my proc:

06502: PL/SQL: numeric or value error: character to number conversion error

If I remove the 'E', it runs without error. Since this is just a CHAR to VARCHAR2 conversion, why should I get this error? I have tried to fix it by setting the field to TO_CHAR(DB2 field) on the update, but then I get this error:

PLS-00307: too many declarations of 'TO_CHAR' match this call

Any ideas?
BTW, using Oracle 8.1.7.4

Thanks.