thanks so much - I wasn't connected up to my printer - as you suggested. I can now print!
But I've been juggling the dimensions to fit my labels, (none of the Staples formats seem to fit, even though I've got Staples labels) which all seems fine except now when I print it out it's cutting off 13 millimetres above the bottom edge. i.e. I'm printing 2 labels on one sheet - duplication, the top one is more or less OK but the lower one has got a flat bottom instead of being a whole circle.
What d'you think?