Hi Guaravvirdi,
The initial F&O posting of the expense report hits the integration account as it passes into the CE side. Once it is in CE it is then taken back into F&O through the staging table to be posted through the projects module using the project integration journal where it picks up the correct ledger account for the expense category. The below diagram shows the flow of data:

In F&O terms it is doing the below postings:
Expense Report:
Dr Integration account specified in PMA Parameters
Cr Employee AP account
Expense posted as actual in CE and imported into F&O Actuals staging table
Project Integration journal
Cr Integration account
Dr Project Category ledger account (Posting type "Project - Cost")
You might want to check the "Project Integration journal" menu item for the related integration journal if you can't see the expense transaction against the project in F&O.
Hope this helps to clarify.
KR
Mark