strange 'create mask' problem

[Eric Yellin]

I am running Samba on RH 7.0 over a router. I defined a share as
follows:

[share1]
   comment = Share 1
   valid users = user1 user2 ...
   path = /var/www/temp
   public = no
   writable = yes
   create mask = 775

The share works fine however when creating a file on the server it is
given 0764 permissions instead of 0775
I played around with the 'create mask' values and finally was able to
get 0775 permissions by setting it to 766...
Any ideas???
Thanks,

Eric Yellin