[Samba] smbumount will not let me unmount

[Nir Soffer]

The smbumount manual says:
	"With  this  program, normal users can unmount smb-filesystems, provided
        that it is suid root. smbumount has been written to give  normal 
  Linux
        users  more  control  over  their resources."

I installed it as setuid root:
	-rwsr-xr-x    1 root     root       618675 Apr  7 23:11 /usr/bin/smbumount

Then I use smbmount to mount a share:
	smbmount //server/share ~/mntpoint rw

And it works fine. But when I want to unmount it as a user:
	smbumount ~/mntpoint

I get this error:
	You are not allowed to umount /home/nir/mntpoint

So what is the (mount) point in this? what am I doing wrong?

btw - I also installed smbmnt as setuid root - otherwise it will not let 
me mount at all as a regular user.