Logitech asked me to post my problem I sent to them here in this forum.
For the sake of simplicity, I copy the mails from the Logitech's support page (read bottom to top).

I hope you can solve this problem.
Thanks in advance for your help.

Manfred

SB firmware version: 7.7.0 r9546

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Response Kaizer Kristina via Email 05/12/2011 06.54 PM
Hello Manfred,

I believe you are right that they may do their streaming in a different way. From what I can see they are streaming in the proper format there just may be some restrictions, it could be location related - some stations will only allow playback in certain countries - or there could be player restrictions. I did manage to have it play for a mere 10 seconds before buffering and stopping.

At this point this seems to be an issue with the station streaming to the Squeezebox and our Engineers would have to take a look at this. In order for this process to begin please post this inquiry to the following links:

https://bugs-archive.lyrion.org/

http://forums.slimdevices.com/

Please provide as much detail as you can when you post.

Regards,

Kristina
Logitech Technical Support-North America
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Customer Manfred Peters via CSS Web 04/12/2011 07.44 AM
Madam or Sir,
thanks for answering my request.

your questions and my answers:
>What are the call letters/call numbers of the station you are trying to listen to?
I repeat the information that was given in my first request (see communication history):
http://opml.radiotime.com/Tune.ashx?id=s78716&formats=aac,ogg,mp3,wmpro,wma,wmvoice&partnerId=16&serial=1cbf405e01e9beacadf80aea5ef3e077
the name of the station is: Radio Leverkusen

>Have you tried searching for the Station in Internet Radio>Search?
yes. That's the way I got hold of the above address in "mysqueezebox.com".
I searched it with
HOME / TUNEIN / SEARCH(Radio Leverkusen)
The first hit (the one with the yellow sign (Radio Leverkusen 107,6) is the correct station.
When I select this one the logo is displayed and nothing more happens...

I know that Nacamar (the stream provider) uses a tricky kind of authentication to make things for audiodevices like smartphones/squeezeboxes etc. harder (no advertisement is displayed in contrary to a browser usage...).
Some time ago I talked to the guys from TuneIn about this problem. They changed their Android version. Now I can play this station (and this problem relates to all stations streamed by Nacamar) without any problems. It takes a while for the start (up to a minute. Must be the authentication part) but then it works flawlessly.

Here are two more URLs for Radio Leverkusen that work in a browser:

http://edge.download.newmedia.nacamar.net/sltokens/stream-radio-player.php?stream=radioleverkusen/livestream.wma
this is a direct link to the stream.

Another one is
http://tiscali.project-fx.de/play.wma?radio=rlev
this friendly guy manages the session authentication and then passes the stream on to the caller. That works for some devices (see the main link http://tiscali.project-fx.de ), but unfortunately not for the squeezebox.

Hope this additional information helps to solve the problem. I am very satisfied with my squeezebox and would be totally happy if I hear Radio Leverkusen too...

best regards,
Manfred
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Response Kaizer Kristina via Email 03/12/2011 07.28 PM
Hello Manfred,

Thank you for contacting Logitech Customer Care.

What are the call letters/call numbers of the station you are trying to listen to?

Have you tried searching for the Station in Internet Radio>Search? If not, I suggest doing so, if all plays well you can save as a favorite by pressing the + button and adding to Favorites.

Regards,

Kristina
Logitech Technical Support-North America
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Customer Manfred Peters via CSS Web 25/11/2011 07.15 PM
madam or sir,
it's not location related. I have the same problem when I try to access RADIO LEVERKUSEN from germany or elsewhere on the internet...
it's purely a technical problem.

So please forward this information to your technical department...

Best regards,
Manfred Peters
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Response Szilvia B via Email 25/11/2011 03.56 PM
Dear Manfred Peters,

We understand that you are having issues with your Logitech device.

Unfortunately, you have contacted the Logitech Europe, Middle East and Africa Support team so we will be forwarding your case to our Asia Pacific counterparts to assist you further with your concern.
Please bear with us, and rest assure that your case will be taken care of at the soonest possible time.

If you have any additional questions, please feel free to visit our website at http://www.logitech.com, or reply to this e-mail. If you need assistance with logging into your Logitech.com account and/or updating your support incident, you will find the below FAQ’s of assistance.

Answer Title: Logging into my account on Logitech’s support site
Answer Link: http://logitech-en-amr.custhelp.com/app/answers/detail/a_id/16704

Answer Title: Using my account on Logitech’s support site
Answer Link: http://logitech-en-amr.custhelp.com/app/answers/detail/a_id/16705

Kind Regards,

{agent’s name}
Logitech Europe S.A.
Customer Care - Europe, Middle East and Africa

Please note: While waiting for your response, we put all support requests to a waiting status. If we do not hear back from you within 2 weeks, we assume that your request is solved and change its status accordingly. A survey will then be automatically sent asking for your feedback. If you received a message saying your support request is solved, you can still write back to us by responding to the last email and update your support request.
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Customer Manfred Peters via CSS Web 25/11/2011 09.43 AM
Madam or Sir,
the above is my preferred radiostation in Germany. You can configure it online/in the radio. The address is
http://opml.radiotime.com/Tune.ashx?id=s78716&formats=aac,ogg,mp3,wmpro,wma,wmvoice&partnerId=16&serial=1cbf405e01e9beacadf80aea5ef3e077
unfortunately the only thing that happens is the display of the logo, no sound at all.
I know that Nacamar (the streaming provider) uses a tricky kind of authentication. But the problem is solvable.
The guys from tunein worked on their Android app and made it happen...
It takes nearly a minute to come up, but if running once it's fine.

So, it would be absolutely fantastic if this magic would also work with my beloved Squeezebox.

Thanks for your help. I hope to hear this station in the near future (I'm currently in Thailand...)

Best regards,
Manfred Peters