Hi,
And that is exactly the case, delta load considers only changes on records whose parameters are in range of restriction of InfoPackage which initialize delta.
In my particular case initializing InfoPackage had restriction on documents from 2010 to 2099 and since closed items that were making problems were from 2009 delta didn't consider this as change and didn't transfer it to BW.
Hope this helps if you had similar problems.
Regards,
Mijodrag