First of all, this may seem easy if you know the answer, but I have been searching this on many forums/google, and have not found the answer.

Ok I have a worksheet (a sort of database). Column A has the Reference code (e.g. TE123), and all the other columns have the related information

I have another workbook (a timetable) where I manually enter the reference number, and the information provided pull through. (This has to be a manual entry, so I can decided where to put it.

All I want to do, is to get a formula/warning, that shows any reference code that has not been entered into the timetable.
So effectively, i need a formula that searches the whole of the timetable, and returns a value of false if not found.
Better still, it would return a value of how many times the value was found

Many thanks in advance.

Simon