Conditional Formatting Borders Stoped Working

[scottrperry]

I have a column with a series of items, some of which repeat. The repeated items need to appear grouped together.

I set the horizontal borders between them as heavy lines and added a conditional format that checks to see if the content of one line equals the line above, and if so changes the top border to a thin line. This leaves the thick lines between differing items, and places thin lines between matching items.

My problem is it stopped working. It continues to recognize the matching cells correctly, but no longer applies the thin borders.

I'm in Excel 2007.