Problem with VCDS / HEX-V2

Hello experts, a beginner needs help.

Brief description.
A VW T3 bus (manufactured in 1989) with an electronically controlled 81 kW (110 hp) diesel engine.
All the relevant components for the cruise control system were properly wired according to the plan, and they were already functioning after the cruise control system was activated. After making a small modification (improving the components, specifically the clutch and brake switches), I want to re-enable the cruise control function, as I have done before.
Now, the following error occurs:
I ran the connection test (using the default settings), and it worked.
For example, I choose "motor electronics."
Ignition is on, the green light on the VCDS connector is blinking slowly.
As soon as the engine control unit reports an error, the red light starts flashing.
The control unit is responding, and I can read its data, etc.
I want to activate the cruise control, which used to work, but it's not working anymore.
Whether I access the control unit, for example, the immobilizer, every time the device logs in, the red light flashes in between.
In my opinion, it has nothing to do with my small modification to the cruise control.
Perhaps I messed something up with VCDS.

Hello,

and what exactly is the error? How about a Screenshot?

Best regards, Rainer.

Hello Rainer,
Thank you for the quick response.
I've figured out the issue with the cruise control.
A follow-up test is also fine. No error message.
I can also access, log in to, and read data from control units.
The light on the VCDS connector is blinking green. Why is the light on the VCDS connector blinking red as soon as a control unit logs in? Is there an error? Did I change something? No matter which control unit I click on, the light on the connector blinks red as soon as it logs in. Is that normal? Is that normal?
Is this a subtle issue, since everything else seems to be working fine?
In my opinion, a Screenshot isn't very helpful; I would need to create a video so that you can see when the light starts flashing red.
I already described that.
I'm a beginner with VCDS and still have a lot to learn.

Best,
Toni

You should have a HEX-V2. If it's blinking green/red, that's normal.
Okay, I'm ready. Please provide the German text you want me to translate.

Hello Rainer,
Thank you very much for the very quick response.
Yes, I have this VCDS.
Then everything is clear, and I know that this is normal and that I haven't made any mistakes.

Best regards,
Anton.