Hi,
I've added a few brackets to your code and changed the logic slightly in the middle...
If ({DEALS.CPARTY}="2254" or {DEALS.CPARTY}="1103") and {diaryrpt.CCY}<> "GBP" then "Auto Debit Credit"
else
if ({DEALS.CPARTY}="1208" or{DEALS.CPARTY}="1140") and {diaryrpt.CCY}="GBP" then "Auto Debit Credit"
else
If {@REC/PAY}= "PAYMENT" and {cparty.DEAL_INT}="N" then {cparty.CODE} & {diaryrpt.CCY} & {diaryrpt.TRANS_TYPE}
else
if {FACILITY.NAME}="NONE" then {DEALS.CP_REF} else {FACILITY.NAME}
else
""
Have you checked that your output is blank and not null?
Try changing the 'Exceptions For Nulls' option to 'Default Values For Nulls' and see if that makes a difference.
Cheers,
Matt