Are you on a layout based on the Main_Page table ?
If not, that calculation will not work and will conditional format EVER the second record's field EVEN if not = to the previous.
"...Surname Field will be greyed out, or even appear blank."
To let it appear blank, conditional format the text to be 150 points.
Yes, the Surname Field is in the Main_Page table. The Layout also shows all records from the Main_Page table.
But for some reason the conditional formatting only applies to the second record only. The formatting is the easy bit....
Interesting, Mitch, it works for me. Are you saying that, if sorted by first name that the conditional format on surname should properly grey out as well? It would but only if it met the conditions by looking at the record immediately above it.
I am curious now why it won't work for your file. Can you please tell us your FM and OS versions? Also, seeing your file might help identify the issue (you would need to upload it somewhere and then provide a link).
UPDATE: Actually, I created a demo. Could you see if this file works as you expect and if not, further explanation/information will be helpful. :^)
Yours does work. I have just checked if the correct fields and correct tables are applied. One of the fields was from another table and therefore would not work, the other fields would. I placed this feild in the correct table and made it a lookup. All works OK.