I'm unable to work with Events using APIv2 (PHP).

Just after getting a fresh Event ZCRMRecord object from ZohoCRM I'm trying to upsert it and it gives me an exception:

[INVALID_DATA|400] "the given module is not supported for this api"

And after I unset the Id and try to insert a new Event (based on existing one, just removing the Id) I get:

[INVALID_DATA|400] "invalid recurrence pattern" (Array(

    [expected_data_type] => RRULE

    [api_name] => Recurring_Activity

))

I tried to unset the Recurring_Activity field, set it to NULL, empty string, rrule string - nothing helps.

Can anyone give me a hint?