Crystal Reports Highlighting Expert

Message

     I would like to setup a highlighting expert that highlights a field if the date of the another field is greater than the number on another field.  An example would be I would like the PO to highlight red if the PO Date is created than the last leadtime date. 

PO Date           PO              Last Leadtime
2/1/11              80000         2

So if the report would run today I would want it to highlight the PO on this because the last time this PO created it was delivered in two days and now it is last two days.

Is this something that could happen.

Thanks