perm error on mount point

I've a problem with mount.cifs using kernel > 2.6.24 (so with cifs > 1.52). With some shares, permission on the mount point
are not applied.

Test on debian base distro (kernel 2.6.26-2), when i mount using the option dir_mode=0755, the mask is not apply to 
the mount point but just on the sub-dir. This problem occurs on some windows shares (that are automatically 
made by a external program on my windows 2003 server). 

With the share "MYSHARE" : error (same error if i don't use dir_mode option)
$> mount -t cifs //192.168.224.1/MYSHARE$ TEST -o username=admin,uid=10066,gid=10000,dir_mode=0755 --verbose
$> ll .
dr-xr-xr-x 1 admin utilisa._du_domaine    0 jun 11 17:14 TEST

With other share "OTHERSHARE" : ok (event if i don't use dir_mode option, permission are corrects)
$> mount -t cifs //192.168.224.1/OTHERSHARE$ TEST -o username=admin,uid=10066,gid=10000,dir_mode=0755 --verbose
$> ll .
drwxr-xr-x 1 admin utilisa._du_domaine    0 jun 11 17:14 TEST

If i booted from kernel 2.6.24 with exactly same command, everything works as expect for all shares:
$> mount -t cifs //192.168.224.1/MYSHARE$ TEST -o username=admin,uid=10066,gid=10000,dir_mode=0755 --verbose
$> ll .
drwxr-xr-x 1 admin utilisa._du_domaine    0 jun 11 17:19 TEST

I use mount-2.13.1.1-1, smbfs-3.2.5-4lenny2 and samba-common-3.2.5-4lenny2

So why with kernel 2.6.26 dir_mode is not applied to the mount point on some share whereas with 2.6.24 it always works !