I activated and deactivated the Fontend::NotifyModule##5-Ticket:TicketEscalation module and now OTRS fails with the message

Illegal division by zero at ../..//Kernel/System/Ticket.pm line 2103.

I have got the system up and running again by commenting lines 2103 to 2107 in /Kernel/System/Ticket.pm which are:

#my $Reached

#   = 100 - ( $WorkingTime / ( $Escalation{ $Map{$Key} . 'Time' } * 60 / 100 ) );

#if ( $Reached >= $Escalation{ $Map{$Key} . 'Notify' } ) {

#    $Data{ $Map{$Key} . 'TimeNotification' } = 1;

#}

Any ideas what’s gone wrong and how to fix it without cutting out bits of the ticket module?

Regards,

Marc