No state update of closed tickets after customer webrequests

[mahoe]

Hello,

I`m having a problem with the ticket state update after a reply to a closed ticket via the OTRS customer web frontend since I am using OTRS 3.0.7.

I try to describe the problem with the following situation:
1. A ticket has the state "closed successful" and is located in the Archive & Restore Queue
2. A customer replies to the ticket via the customer web frontend (reply button).
3. After the reply the ticket usually should have the state "open" but in my system the ticket still has the "closed successful" state.

I do not really know if it`s a configuration problem or an error in OTRS 3.0.7. I just know that this worked correctly with OTRS 2.3.4 we used before.
The relevant config entries for Ticket -> Core::PostMaster are
* PostmasterFollowUpState is set to open
* I also activated PostmasterFollowUpStateClosed and set it to open

I found a strange history entry of the ticket for the reply sent via the customer web frontend:
> FollowUp FollowUp für [ ].
(no ticket number between the square brackets)

When I open the closed ticket with a usual mail the entries of the history look like as follows:
> StateUpdate Alt: "closed successful" Neu: "open"
> FollowUp FollowUp für [1107403].

Does anybody have an idea what`s causing my problem?
I appreciate any help.
Thanks in advance!

Greetings
Markus