Live File System formatting problem

"Have DVD+/- Drive and using Live File System, Version 2.01 to copy files as
routine backup. But it’s not working for me at present and I am getting
increasingly frustrated!!
Trying to save a folder containing 20.3MB of photos to a CD-RW which has
295MB of free space. The “Burn a Disc� Dialog box comes up with live file
system as default. When I click on “Next� I get "Warning! Formatting will
erase all data on this disk", with the alternatives to click OK or Cancel.
So I cancel, not wishing to lose valuable files already saved! Previously I
successfully saved a folder containing 5.53MB of photos to the same disk plus
other files. So why not this time? Why is it trying to format again?