Chronos link not working

Hi, my postdoc has set up an experiment using E-prime 3, Chronos and a Digitimer DS7A adapted. The experiment sends simple signals associated with events as part of a larger experiment. This was working during her time in my lab. Since I've tried to re-run this, we are getting an error message saying no such attribute as "DigitalSignal". This seems to relate to a parameter in the task events for chronos, but it's not clear to me why this would suddenly stop working. Any thoughts on the type of problem this might represent?

Thanks