More details? New show, new series, existing series, etc?
I have found that when a show first appears in the guide (about 10-12 days out), it often can be set to record, but not as an SP. Wait 24 hours, and the SP option appears. This happens on a consistent basis.
And of course the show has to actually be a series. And not a one-off.
"Happiness is not about doing, it’s about being." - R Branson