how to import GPG Keys in Uyuni (RepoMDError: Cannot access repository. Maybe repository GPG keys are not imported)

Hi List, i added " https://downloads.linux.hpe.com/SDR/repo/spp-gen10/SUSE/15/x86_64/current/" as a custom channel in Uyuni. If i want to sync its repo with checked "Has Signed Metadata?" Box i always get this error in my reposync log: RepoMDError: Cannot access repository. Maybe repository GPG keys are not imported If that box is unchecked it syncs fine. - I filled out the "Security: GPG" Fields with data from " https://downloads.linux.hpe.com/SDR/keys.html" - added the Key to "Systems > Autoinstallation > GPG and SSL Keys", and - did rpm --import on my uyuni server Is there a way to add more verbosity to that log so i can ensure i really added the right key (should be gpg-pubkey-26c2b797-5669d0b9)? Thanks, Heiner