The national anthem of the GDR was "Auferstanden aus Ruinen"/"Risen from Ruins", it had the following lines:

"Risen from ruins / And facing the future / Let us serve you for the good / Germany, united fatherland"

during the early period of the GDR they were all for a reunified Germany - but the united Germany was supposed to be a socialist one and modeled after the GDR; therefore the east German constitution of 1949 stated that Germany should be reunited;

Now by the 1970ies they decided that this is impractical; also the GDR was seeking international recognition so that the policy was changed to co-existence between the two German states. (by 1973 both German states had diplomatic relations and were both accepted into the UN, also the 1968 constitution did not mention reunification) and therefore the anthem was never sung in public - you would only hear the music; they did not bother to change the anthem, its hard to do with a song.

Very curious fact, the Soviet national anthem had similar problems: the 1944 anthem mentioned and praised Stalin, but that was changed only in 1977 (incidentally by Sergey Mikhalkov - author of the original text); now extolling Stalin became improper after de-Stalinization, so that between 1956 and 1977 they just performed the music without the words.

This is the sort of inconsistencies that you would get when frequent policy changes require history to be rewritten in order to accommodate said policy changes ; there was an joke for that during this period : "the Soviet Union is a country with an unpredictable past"