I was a bit too quick here. Actually you can omit the double unary minus (--) and get the same result. The formula with -- works fine as you can see, but the same will your original formula =INDEX('Cycle Analysis'!C$3:C$1215,MATCH($B3,'Cycle Analysis'!$B$3:$B$1215,0))="Y". The problem was alone the file type. If you want an explanation of the --, here goes:

Let's say that you have the string ABC123 in A1 and you want to extract 123 (to be used in some calculation). Now you can enter (in B1) the following formula: =Right(A1,3) and get 123. Now try in C1 to enter =ISNUMBER(B1) and you will get FALSE. Try then in C1 to enter =ISTEXT(B1) and you get TRUE. So what appears as a number actually is text which means that you can't use the contents of B1 in a calculation. Now try to put a minus sign just after the equal sign in the formula in B1 so that it becomes =-RIGHT(A1,3). B1 now shows -123 and you will note that C1 (which tested if B1 is text) now shows FALSE. That is, it is now a negative number. Then try to put one more minus sign after the equal sign in the formula in B1 so that it becomes: --RIGHT(A1,3). You will now see the result 123 and observe that C1 still shows FALSE. You can change the formula in C1 to =ISNUMBER(B1) and you will see TRUE. So what is called double unary minus coerces a 'text number' to first a negative number and then to a positive. It is in a way as if you say minus times minus gives plus.