A Cracket marriage in 1777

I have tried tackling my Crackett/Cracket line in both directions: Working backwards from me and working forwards from the oldest I can find in Northumberland. I still have a gap that I cannot close though. The oldest marriage I have found was in Lowick in 1777 between David Cracket and Jane Jackson (Jaxon), but I have not been able to prove yet that they belong to me.