The DENIC checks the Nameserver settings of every UPDATE of .DE domains. If these are not correct, a Nameserver error will be displayed and the Update will fail (UPDATE FAILED).
You can test the Nameserver entries for .DE domains with the DENIC checking tool NAST.
This enables you to detect any possible errors with the Nameserver and the domain settings.
As soon as the Nameserver entries are without any faults and the NAST checking tool does not display any errors, you may again choose UPDATE from the Domain List.