Yes, you're right jpols! I noticed that and modified my script.
code:

shell "%comspec% /c net time \\$computer > %temp%\$computer"
$ = open(1,"%temp%\$computer")
$time = readline(1)
? "$time"
?
$ = close(1)

$minutes = Val(SubStr($time,Len($time)-1,2))+2
If $minutes < 10
$minutes = "0" + $minutes
EndIf

$time = substr($time,Len($time)-4,2)+":"+$minutes
shell "%comspec% /c AT \\$computer $time /interactive C:\Temp\Script.cmd"


Now it works!