Dantumadeel is in Friesland not Groningen, and I am not too sure whatever happened to our Friesland forum here. I guess we are relegated to posting in the general forum for Friesland questions, but we are in the wrong province here. You can find out a lot by just doing a Google search, you would have known that Dantumadeel is in Friesland.
Genlias is only good for searches after 1811 generally.
There is a genealogy webpage for Friesland, it lets you do searches from before 1811, you can click the English flag on the home page for searches in English. http://www.tresoar.nl/