Change row colour based on conditions

Hi,

I'm trying to write a function for my SRS 2005 report what will do the following:

If Stock_Item = 'No' And Shipping_Date - Order_Date > 14 days
Then Row Fill Colour = 'Red'
If Stock_Item = 'Yes' And Shipping_Date - Order_Date > 5 days
Then Row Fill Colour = 'Red'
Else Row Fill Colour = 'White

Can somebody please show me how to do this?

Cheers

Paul