Unable to write to flash drive

I have been going through the paces with running Knoppix 4.0.1 from DVD by following the instructions of the manual contained in the DVD. All was going well until I tried to copy files from my notebook's hard disk to a USB flash drive. The flash drive was recognized by Knoppix and its folders were properly displayed. However, when I dragged files from my hard disk's window and dropped them into the flash drive's window, nothing happened. When I tried to use copy and paste through the edit menu, I got a message that I could not copy but no explanation as to why. In addition, I could not duplicate all of the steps in the instruction manual, e.g., I could not find any way to select 'copy here' from the menus I could access. I suppose that the latter is due to the fact that the instruction manual was written for an earlier version of Knoppix. In any event, how can I manage to copy files to my flash drive within the XWindow environment?

did you remount it read/write?
if not rightklick on the icon and do that.
all disks are mounted read only in knoppix.

OErjan,

Sorry, I failed to select the read/write option initially. I found out how to do this after I posted here and things went smoothly in this respect thereafter but rather badly elswhere. However, the latter I should refer to Knoppix support. Thanks for your reply.