Changes since SOA version
IXFR is a zone transfer request that returns changes since a specific SOA version. Enter the SOA version to request changes since then.
Not an apex domain
The domain uu4p6ac8l9c47lq4tmq80n4b51dpvpkp.sk.eserver.net is not the root of its zone.
Instead, try zone transfer on sk.eserver.net .
Instead, try zone transfer on sk.eserver.net .