I'm assuming that you've checked out the Scotland People's web site www.scotlandspeople.gov.uk and the IGI - preferably at an LDs FH Centre as the online IGI does n't have all records.
I couldn't find them with a quick search on SP.
If there are no records on these two sources, their parents may have been of the non-established church or the record don't exist. Scotlands People have a link to a site which lists the dates for the records for each Old Parish.
Alternatively it might be worth trying to have a look at the Kirk Session minutes in Edinburgh, if you are anywhere near there.