LMBD Resynchronization: System Not Found in Source SLD

Hello experts,

I have created a system in LMDB manually. If I try to start the resynchronization of technical system information from sld, the error messages "Resynchronization of Technical System Information from SLD" and "Technical system <SID> Application Server ABAP not found in source SLD "LMDB Sync with central SLD - <hostname_solman> (sld/active)" appears.

In the help section I found the following hint:

System Not Found in Source SLD
If a technical system was created manually in LMDB and does exists in SLD as well, but cannot be found by resynchronization, check if the names in SLD (Instance Name) and LMDB (Reference String) are different. They must be identical.

I have compared the instance name in T-Code smsy and the reference string in LMDB and there is no difference. I have searched in the marketplace and I've asked google for an answer 😉 .... but there is no snote and no solution.

Maybe anybody has got an idea.

Thanks and best regards,

Max