Langholm Parish registers

[Mavals]

Does anyone know if there is a missing register for some reason?

I have found an entry in 1686 for the birth of John Donaldson, father George (no details of mother given), but the next relevant Donaldson date is 1743 when Elspeth, dau of John Donaldson and Helen Hotson (or Howetson) is baptised. I can't trace a marriage for John and Helen or a birth for Helen anywhere is Dumfriesshire, any dates are too late.

I have looked at Scotlands People, Family Search and the Dumfriesshire baptism fiche at the Scottish Genealogy centre without success. Elspeth appears to be the eldest child, the latest registered child is born in 1755, so I wonder if the John married to Helen could be the grandson of George.

George and John are regularly used family names - even into the 20th C, so I would like to be able to link up to George and John if I can

I am wondering if the registers were lost or not completed between late 17c and mid 18c. Any information would be greatly appreciated.