OA + PMC: Key blacklisted?

[gobbo]

I just tried to install the PMC DLC on my laptop, since I'm not at home this weekend and therefor can't use my PC.
The problem is: When trying to install the DLC following message pops up:

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Arma 2 Private Military Company Setup
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Used serial number for ARMA 2: OA is black listed. Please obtain a valid copy of ARMA 2: OA.
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OK
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The OA copy I'm using is 100% legal bought at a local store.
No one else uses my key, so why could it be blacklisted?
What can I do about that?

Also, some of the missions really require a patch.
Examples:
Convoy mission. Everytime I shoot the Minigun, a script error message, seems to be tracer related.
11: Termination. After I chose not to kill Dickie in 'mission 10', I drove around in the SUV, picking up some weapons and ammo from apparently bugged bodies, there were like 10 identical bodies next to each other everywhere. Then I attacked one of the camps, seizing a mortar. So I went to set it up on a vantage point, until I hit a wall, maybe 10-15cm high. The SUV started flipping and bouncing, up to 30m up in the air, killing both Asano and me, resulting in a ragequit.
If this is the way BIS wants to go, go without me. I've had it pretty much. For 9€ for a few models and a campaign you might expect some special care, not the usual bugged stuff.

After ranting a bit, back to my original question: Why does it say my key is blacklisted?

[Dwarden]

let's continue in PM