"Skip" in Import Format not skipping some rows

Question

We are currently using FDM 11.1.1.1.00 and we have a problem with skipping lines based on currency (which is our AccountDescription).
We first extract 28392 lines from Oracle EBS (27921 CAD and 471 USD). No mather what we put in the skip condition, the generated .dat contains exactly the same data (file compared with UltraEdit).
If we set our import format to skip USD lines, 11 of them are still imported. It's the same behavior if we set the import format to skip CAD lines (1136 of them are still imported).
For example this line still load
2021;1115562;50308;E;;006;806050;0000;55365;001;0000;;;;;;;;;;;;;;;;;;;;;;;;;USD;P02-13;A;;;2013;3.06;22.08;-19.02
while this one don't
2021;4368;50308;L;;101;000000;0000;21350;001;0000;;;;;;;;;;;;;;;;;;;;;;;;;USD;P02-13;A;;;2013;2400000;17100000;-14700000
***(Skip is on field 36 (USD))
I looked at some of the lines still loaded in hexadecimal to find any invisble character or differences in codes used to display characters but they are the same as lines that are skipped.
Three persons has been searching for pattern in data that could lead us to the problem without success.
Any ideas on why thoses lines are still imported ? Where should I look at ?
This may be easy to solve, but I'm new at this stuff (I actually had to learn FDM by myself as all technical administrators knowing it left the company).
Thanks.

Answer 1

Thanks for your help. It works fine with the script. Now it return only the rows I need.
I only inverted the condition so if it's CAD, the function return the value, else it skip the line (to exclude USD, EUR or any other currency it may encounter in the future).
Thanks again.
My script looks like that :
Function SelectCADLines(strField, strRecord)
'UpStream WebLink DM DataPump Import Script:
'Created By: Francois Robineau
'Date Created: 2/19/2013 10:35 AM
'Purpose: Select only CAD (skipping USD, EUR or any other possible currency)
Dim strAccount
'Store first value of account
strAccount = strField
'Check to see if value is CAD
If strAccount = "CAD" Then
'Return line
SelectCADLines=strAccount
Else
'Skip line
Res.PblnSkip=True
End if
End Function