Digital BW, The Print

Hi all, 

I finally got an r1800 and am ready to go with the 3Mk set-up (very excited!). However, I am 
stymied by the fact that the paper I'm loading (HPR) keeps passing right through the printer.


I googled and came up with something about a thick paper check box in the photoshop 
printer dialog....but I can't seem to find that (I'm on a mac with PSCS....the first one.).

I suspect I am missing something that's staring me right in the face....anyone?

Thanks,
Sarah