how to mount a patition under which i can ln .

[zhaoh at cnic.cn]

my /etc/fstab:
/dev/hda6 /mnt/winshare/ vfat defauts，umask=0 0 0 

I use ln command under this patition:
ls -s /mnt/winshare/testfile /mnt/winshare/symtestfile,
i got the reply：no permission to ln.

Pls give me any suggestion.

Thanks in advance.