Absence registration for profiles without Clockin-Clockout

How to register a Vacation Absence for a worker if is used a Flexible time Profile (“24-7” in this case)?

At the moment if I create an Absence manually for 6/10/2014 and I check “Calculated” checkbox, the Absence is deleted

There are no ClockIn or ClockOuts for this profile, see below:

See below Profile declaration:

0714.6-20-2014 12-19-53 PM.png

And Approve form