How to put 'text' into a conditional format

[nje]

The solution to this escapes me, but I'm sure it's quite easy. I would like column H of my sample file (attached) to change colour and say 'Service Due' when it comes within 60 days of the service date in column D.
It changes colour, but I cannot workout how to put the text message into the cell. If there is a betteror easier way, then as always I'm open to suggestions
Thanks