Missing signup_time in new created events

I'm coding an education and training administration with the help of sign up, event manager, views and CCK. I've got a summary in a table view for all my events where they are sorted by 3 columns: "last update", "last comment" and "last sign up".

Everything works fine when users subscribed to an event, but when an event is created and no one has signed up yet it isn't displayed in the summary. I can edit and even see the event in other views, but it's missing in my summary. When the first user signs up it comes up in the right order in my summary. When i delete the "last sign up" column it works too ( naturally without the sort order of the last sign up).

I've found out, that the timestamp ist saved in "signup_log" as "signup_time". Signup creates the log automatically when someone subscribes, else it doesn't exists (there would be no problem if the table would be empty, but it simply doesn't exists.) So i need an option that when there are no sign ups that the signup_time is 0 (=never).

When i add a timestamp on my own signup subscribes an unauthorized user an this is wasting my available slots. Perhaps i can add an "option" in the "Signup: User: Signup Time" field when i edit my summary ?

Greetings