[otrs] Survey-key invalid error

Hi I created a survey for my company and set the status to Master and set it such that every time a ticket is closed, it sends out the survey to the customer. In the customer's email, it would have a link to open the survey and when I try to open the link, it displays "Survey-Key Invalid" error message. Settings I have in my Sysconfig are as follows : *Ticket::EventModulePost###99-SurveySendRequest*: Event : (TicketStateUpdate|StateSet) Module : Kernel::System::Ticket::Event::SurveySendRequest Could anyone please let me know how I can fix this error ? By clicking the link in the survey email, customer should be able to take the survey without any interruption. Winter