Danish enigma

I live in Scania in southern Sweden and am from my childhood well
acquainted with our Danish sister-language, reading books and
listening to radio and TV programs fairly fluently.
There is one expression, however, that, though I understand it fully
well, I can't analyse as a linguist: "... det er lykkedes (os at)..."
This expression is completely contrary to my Swedish "language-
feeling". What is "lykkedes" in this context? How is it to be
described as a verb form?
We have in Sw. and Da. the same verb "att lyckas", "at lykkes" (to
be successful, to succeed in, to be lucky to). The verb ends in
passive -s but has no active forms, thus a deponens.
I have heard that Danish does not tolerate synthetic passive with
ending -s but for simple verb forms (present and preterite) and forms
passive analyticly in perfect etc with auxiliary "er blevet ...".
Ex: Bogen skrives (The book is written), Bogen er blevet skriven
(The book has been written).
In Sw. perfect can be constructed both with -s and the auxiliary
'bli(va)': "Boken har skrivit-s, Boken har blivit skriven".
In deponent verbs however only -s is tolerated in perfect:
"Jag har lyckat-s" ("Jag har blivit lyckad" would mean something
totally different: I have been a success (to my proud parents).
Therefore my question is (directed primarily to Torsten and other
Danes on this board): Is "lykkedes" the way of forming perfect of a
deponent verb in Danish? Or is it to be analysed in a completely
different way?
Thanks beforehand
Lars