Peek Previous lookup all returns '-'

[43918084]

I have below table.  The first 2 fields are loaded table fields. The 3rd field is what I want to achieve.

The logic is if the Trade Num is the same as the previous, return the previous ACCTG DATE, otherwise returns blank

As I m a new to the tool, I first try to test if I can get the previous ACCTG DATE using

Peek(TRADE NUM, RowNo()-1)

or Previous (TRADE NUM)

or Lookup('ACCTG DATE', 'TRADE NUM', TRADE NUM, 'TABLE')

All returned -. 

Hope I can get some expert guidance

ACCTG DATE	TRADE NUM	Previous Acct Date
20191231	503232H
20200131	503232H	20191231
20191231	503237H
20200131	503237H	20191231
20191231	960509H
20200131	960509H	20191231
20200131	1096601H
20191231	1096602H

[43918084]

Really sorry, I still get '-'.  Below is the script I use.  Sorry my fieldname is a bit long in the original version. I thought I should simplify it in my question . Hope you don't mind that I provide the actual fieldname for your review.

Load
"GLOBAL TRADE NUM (P0221)",
"ACCTG DATE (P0045)",

Rowno()-1 as row,
recno() as current,

Peek('"ACCTG DATE (P0045)"') as check,

 RESIDENT [LYCM]
 order by "GLOBAL TRADE NUM (P0221)","ACCTG DATE (P0045)" ;
 
Drop Table [LYCM];

[marcus_sommer · Accepted solution]

Try it with a change to:

Load
"GLOBAL TRADE NUM (P0221)",
"ACCTG DATE (P0045)",

Rowno() as CurrentRecord,
recno() as SourceRecord,

Peek('ACCTG DATE (P0045)') as check,

 RESIDENT [LYCM]
 order by "GLOBAL TRADE NUM (P0221)","ACCTG DATE (P0045)" ;
 
Drop Table [LYCM];

[43918084]

Thank you very much. It works now.  I really appreciate your patience.