Samba shares only work in read only

Hi,
i tried to share the SD card with Samba.
I installed the samba package and configure with luci.
The problem is that i can connect from windows machine but just in read-only.
The configuration file /etc/config/samba look like this:

config 'samba'
option 'name' 'OpenWrt'
option 'workgroup' 'OpenWrt'
option 'description' 'Samba on OpenWrt'
option 'homes' '0'

config 'sambashare'
option 'name' 'share'
option 'path' '/mnt/sda1'
option 'guest_ok' 'yes'
option 'read_only' 'no'

this works for me ...