I'm having a problem with a conditional format formula disappearing from a cell when I paste another cell's contents into it and then delete the content.

I always thought that conditional format formulas were separate from regular cell contents (like numbers, text, formulas). So if I have a conditional format in a cell, then put some content in it, then delete the content, the conditional format should still apply to that cell.

I have a red border conditional format in a cell, that says if the cell 0 (i.e., if there's content in it) the border should not appear. The CF rule works fine, and when I paste the content of another cell into the CF cell the border disappears as it should. But then, if I delete the content, the CF format disappears from the cell: The Conditional Formatting Rules dialog box shows no formula is in that cell.

The cell whose contents I copied had no conditional format.

In case it's useful, here's the CF formula:

=IF(AND($K$1920,$L$1920,$M$192=0),TRUE,FALSE)

All cells involved have a standard format as well; they're all date formats. I'm using Excel 2007.