The problem is the length of my uid : 26. As dcmtk can add up to 48 characters, I am way over the 64 limit. I am already at 64 before the "counter" has been added
Does anyone know how I can go through that? (without changing my UID of course ).
Since you are using a different UID root anyway, you would be free to modify the UID generation algorithm to something different (shorter). Maybe you can invent something that is still unique. If you can guarantee that every instance of your software will always have a unique version number, that should be fairly trivial. If not (like with the generic DCMTK), things get much more complicated.