[Samba] Samba Write List Macro Not Working

[SerpentMage (Christian Gross)]

Hello, I have the following share configuration

[%G]

    comment = %G global share

    path = /home/shared/%G

    public = no

    browseable = yes

    printable = no

    write list = @%G

My question here is why can I not write to the share, when I can connect 
to the share?

I tried the following version of write list

write list = @%G @%g %U %u

Nothing works...

If I do the following

write list = @%S

then it works...

Could somebody please enlighten me?  Thanks

Christian Gross