> I have updated the post to make it more clear what's happening.

no you haven't, please see SSCCE for the next time.

update

FWIW: your approach is still wrong and will only sometimes produce correct results.

See 1nickt's reply with ->delta_days for the correct solution

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

In reply to Re^3: I can't subtract one DateTime objects from each other to get a DateTime::Duration in days (updated) by LanX
in thread I can't subtract one DateTime object from another to get a DateTime::Duration in days by Cody Fendant

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