Unless you have something funny in your dataset you date fields will never be null.
As far as showing a short date you can also write it like this
Look at your incoming data and see what the date column is coming in as.
We use something like this at my work...
.Value) = "1900") = True," ",Fields!ShippedDate.Value
to use as a textbox/fields filler.
I would try this on your hidden row
sts.Value = "Hep B Series 3",true,false)
Let me know of you need more info.