Condtional formatting based on dates

[rz6657]

The attached file has a planned (PLN) and actual (ACT) dates.

For the planned dates (PLN), I have a conditional formatting formula that highlights the cell when the date is within 20 days of expiring / passing. However, once the date expires (i.e. PLN date = 2/14/13 and TODAY date is 2/15/13), the cell will no longer highlight the cell.

I need a formula that will highlight the cell even after the date expires AND the actual date has not been updated (adjacent column of each PLN | ACT date(s)). Once the actual date is updated in the corresponding cell, than no longer highlight. I've tried conditional formulas but can't find one. Or is this a VBA task?