Complex DTS

I am attempting to pull out selected information from and Access database and output it as a CSV file. The issue arises when I need to replace all commas in the Customer field with some string, in this case #dlm#. If I remove the REPLACE function the DTS works fine, I add it and I can no longer populate the source fields for the transformation. Has anyone had any problems like this? I've used IIF function and it worked fine, so I don't understand where the REPLACE function has problems. If you have any other methods of accomplishing the same task please let me know.

Thanks,

Brad.

SQL statement:

SELECT [case details].Customer_UID AS src_cntct_id, "1" AS cntct_status, "" AS prod_build, [Customer_UID] & [Site] AS person_site_id, [case details].Customer_UID AS person_src_code, "" AS person_first_nm, "" AS person_last_nm,

REPLACE([case details].Customer,',','#dlm#') AS person_full_nm,

"" AS person_phone_1, "" AS person_phone_2, "" AS person_email_addr
FROM [case details];