Dears,
I am from Stettin (Szczecin) near Altdamm (Dąbie) in Poland
So I think correct text will be:
Robert Gröhnke, altdammer (Pommern)
Altdamm name of city = here there is airfield near Stettin.
altdammer means member of city Altdamm or soldier from Luftwaffe unit in Altdamm - here was Luftwaffe School (A/ B 118 Stettin-Altdamm).
http://www.ww2.dk/air/schule/ffsab118.htm
Airfield in Altdamm-Stettin (Areoklub Szczeciński):
http://bi.gazeta.pl/im/8/4894/z4894888X.jpg
http://www.archiwum.radioszczecin.pl...1280429760.jpg
http://www.cantows.de/ahnen/LuisKart1.jpg