Question on date specific pricing

[lbpdk]

I have searched for help on "date specific pricing", but nothing comes up. The wiki also provides no answer. I might have misunderstood the purpose, but my guess is that you have one price between certain two dates, and then another price between another two certain dates. Dates can also be "forever".
I am able to enter two dates in the first price group. But when I try to enter dates in the second price group (after "Add new price"), the newly selected date goes into the date field of the first price, and the calendar pop-up stays open.
Anybody who can help with this?

Joomla: 2.5.19
VM: 2.0.26d

Regards Lars