Oracle Receivables last transaction entered against a customer

We have Oracle E Business suite 11.5.10.2. I have written an sql script to try and find the date last transaction entered against each customer. My script is not working and I was wondering if some could point out what is wrong or how I can correct it?

select

a.trx_date,

a.trx_number,

k.description batch_description,

l.name batch_name,

k.name,

a.complete_flag,

a.status_trx,

b.line_number,

b.line_type,

b.description invoice_line_desc,

c.gl_date,

c.amount,

d.segment1 "CO",

d.segment2 "CC",

d.segment3 "PROJ",

d.segment4 "OBJ",

f.party_type,