Thanks for the advice. Now I clearly understood the problem.
Unfortunately, it will take a few more days until I can get a basis support so now I'm looking for a workaround I can take. One possible option that I'm thinking now is, using a CTS no. which was created in DEV but not released and finally deleted.
I just compared both Reference and Development systems and found one candidate no. Do you think this idea is applicable? Or it is still not valid even though it was previously deleted and not released?