aastra 6731! daylight saving problem.

[hmd810]

Hi I set daylight saving in aastra.cfg like below.
The problem is it doesn't work correctly when I set date of ntp server to 2015/9/20 and time. 20:00 it shows time 20:00 instead of 21:00. How can I solve the problem ؟

# Time Server Settings
## =====================
time server disabled:0 #server enabled(0), server disabled(1)
dst config: 3 #daylight savings, OFF(0), 30 min summertime(1), 1h summertime(2), automatic(3)(default)

time server1:010.010.031.004
time server2:010.010.031.004
#time server2: # least one time server IP address or
#time server3: # qualified domain name

#Tim and Date Settings
time zone name:Custom #Required setting if time-server is enabled
time format:1 #12hours(0), 24hours(1)
date format:2 #YYYY-MM-DD(2)
time zone minutes:-210

dst minutes: 60 #Amount of minutes to add for DST
dst [start/end] relative date: 0 #1 = relative, 0 = absolute
dst start month: 04
dst start day: 02
dst start hour: 00
dst end month: 09
dst end day: 29
dst end hour: 00