Certainly. You are very welcome.
Index-match breaks down something like this:
INDEX ( Answer Range , MATCH ( Single Search Criteria , Criteria Range , 0 - exact match -))
So, in english, this will take the search date and find it in the row of dates, then return the corresponding reference number. The only hiccup was that on Sheet1 the dates were text fields and on Sheet2 they were a numbers. I added zero to the search date within the formula to correct the format.
Hope this helps,