Project expenditure organization coming incorrect

Hi,

When an employee enters expenses against a project, the Project expenditure organization that gets pulled should be the org to which the emplooyee is been assign. We have a scenerio, where the Project expenditure organization is showing different in the same expense report for the same dates. For some of the lines, the current org is showing as Project expenditure organization while for the other, his previous org is showing. I could not find anything wrong in HR assignment. Any idea why this happening.

Regards,

Cesar.