dvd-r?

I've been given my sons old Toshiba lap-top,just to look stuff up on the inter-net and puts some photos onto disc,.I've used cd-r and they are fine but they cant hold alot,so I bought some Verbatim dvd-r's.When I go too transfer the pictures on to the disc,the computer says there is no disc in the drive.I do know that the computer has a re-writer in it and it uses cd-r's,so what am I doing wrong or cant I use dvd's?
Thanks for any help.