Was their marriage in Scotland? if so it should be there as you have the date. Did you use wild cards?
It would be easier to find them on the census once you have their parents' names. Also, the 1901 census is available on Scotlands People and via an Ancestry index, among others.
As you seem to be well into searching the records, it is far more exciting for you to find them, if you can, rather than other people.
Gadget