Linux cp Permission denied on ntfs file system

Linux cp Permission denied on ntfs file system

Could someone kindly explain why I get this Permission Denied error? I
personally am user g and as ls shows I have read and write permission for
both source and destination. My system is slackware 14, and the device
being written to is my ereader, an ntfs-3g file system.
~ $ cp /home/g/MyBooks/Wyndham-TheMidwichCuckoos.txt /500gb/database/media/
cp: cannot create regular file
'/500gb/database/media/Wyndham-TheMidwichCuckoos.txt': Permission denied
~ $ ls -l /home/g/MyBooks/Wyndham-TheMidwichCuckoos.txt
-rw-r--r-- 1 g users 380183 Aug 10 11:04
/home/g/MyBooks/Wyndham-TheMidwichCuckoos.txt
~ $ ls -l /500gb/database/
total 32
drwxr-xr-x 2 root root 8192 Aug 10 11:23 cache/
drwxr-xr-x 3 root root 8192 Aug 5 13:26 layout/
drwxr-xr-x 2 root root 8192 Aug 9 14:07 media/
drwxr-xr-x 2 root root 8192 Aug 5 17:28 sync/
~ $