What projectors are they; what model and what specs? Often, attempting blending with 'normal' office projectors is difficult. If they are industry-based based then you might have better look - due to their quality and features. I am not saying or suggesting you have 'bad' projectors but industry-level projectors are different. Also; pro-level projectors often have their own built-in edge blending tools which sometimes work a bit better than software. I tend to use Panosonics or Epsons built-in Edge warp and blend tools first and then use Izzy to tweak and fine-tune. 

@woland Thanks for the link to the smpte-ltc-to-mtc converter! I've needed this for a while! [https://github.com/Gouttfi/smp...] Cheers!

Dear people
The riddle is solved!

Thanks to the incredibly cooperative Tangent Support, who even installed Isadora Demo to understand the case!

It was simply due to the fact that the OSC naming convention must be followed when assigning the OSC address in the Tangent Mapper.
In contrast to TouchOSC, which already “prepares” the address, the Tangent Mapper requires a “ / ” followed by the address/address variable.
Otherwise Isadora will clearly not recognize the address as such. Hexler protocol does this because it simply auto-completes the address with the missing “ / ”.
It's actually quite simple, you just have to figure it out first 
Now i can go straight forward by controlling  PTZ cams with a colorgrading panel...

In any case, thank you very much for all the tips and your help!
Have a nice week, Tom

@dillthekraut said:

In which version is this new? I can't find it. Same for the Add-Ons.

 If you are unable to find the 'OSC Address Listener' in your Isadora 4.x ToolBin, please open a support ticket so we can work with you to determine why (see link in Signature).

Just a quick reminder to Add System Specs to Your Signature.

sorry @dusx,

I guess this is a misunderstanding. I'm well aware about the 'pythoner' and am very much impressed by it's possibilities. I asked about the 'newer' OSC Address Listener.

@dillthekraut said:

In which version is this new? I can't find it. Same for the Add-Ons.

 Isadora 4 now includes Pythoner. This new python scripting actor allows you to run nearly anything python can handle. 

You should be able to search for 'pythoner' in the ToolBin and add it to your Isadora scene editor, double-click and away you go.

I have created a batch of examples: TROIKATRONIX : ISADORA - Pythoner Example File
An update with even more examples are coming soon, as well as, more video tutorials :)

@nic

Stage Setup window, bottom left-ish.
Also page 179 of the manual :-)

@dusx sounds great but where is "Blend Maker"? I've never noticed it.

@konrad said:

how do I get your User Actors with the extension .iua4 installed in Isadora so that I can use them?

 This is for an older version of Isadora, but the process is basically identical: https://lucaswilsonspiro.wordpress.com/2017/08/28/isadora-set-global-user-actors-folder/