[DMF]Issue when using Auto-generate Option For A field

Hello,

I am new to DIEF
I import a file that contains data about the trade Agreement Journal ( pricediscAdmTrans Table), in my file the column LineNum is absent, so I am generating this column via the option Auto-generated: available under the Tab Map Source To staging > Source Mapping > Mapping Details.
I set the query Criteria for the lineNum To Journal Num.

When clicking on generate Source Mapping it works Fine, then when validating the mapping, the validation is successful.

But when I am clicking get staging Data the stack Trace shows the Following Message:
(S)\Classes\DMFGenerateSSISPackage\generateStagingData - line 282
(S)\Classes\DMFStagingWriter\execute - line 247
(S)\Classes\DMFStagingWriter\runOnServer - line 3
(C)\Classes\DMFStagingWriter\run - line 27
(C)\Classes\DMFStagingWriter\main - line 35
(C)\Classes\FormFunctionButtonControl\Clicked
(C)\Forms\DMFStagingData\Designs\DesignList\StagingWriterBatch\Methods\Clicked - line 33
Issue exist in generate staging data
‘0’ ‘Price discount agreement journal’ record(s) inserted in staging
‘0’ ‘Price discount agreement journal’ record(s) inserted in staging

May you please help me to solve this, I’ve been looking for details about this issue, but with no luck.