Seeking guidance on LISTAGG() function

Summary:

Hello, could someone please guide on why listagg() is not working in the following query:

Content (please ensure you mask any confidential information):

Hello,

We are building a data model aiming to find duplicate item details across multiple BPAs. For example, if values for all fields in SELECT statement are the same, then aggregate the BPA & aggregate BPA line number.

I am working on the query and cannot get the LISTAGG function to work.

Everything works aside from LISTAGG()

Select

esib.item_number,

pla.item_description as bpa_item_description,

hp.party_name as vendor_name,

pla.vendor_product_num,