This script doesn't work, i don't know why

I wrote this machine script to apply a patch to the computers of a OU in a
Windows 2003 Server Domain.

if exist C:\patchs\kbxxxxxx.dat goto end
if exist C:\patchs\. goto label1
md c:\patchs
:label1
\\mcse-01\patchs\WindowsXP-KBxxxxxx-x86-enu.exe /norestart /log:C:\patchs\
echo "patch applyed" > c:\patchs\kbxxxxxx.dat
:end

I gave to the group "Domain Computers" read and write rights over the share
where the patch is located.

I know the script was actually executed because it creates the folder and
the flag file.

Any idea

Thanks in advance