Work importation - by: bioN

hello,
I want to import work for a resource on a project but i don't really get what i have to put in "refType" and "refId" fields. I assumed that it was the type and the id of the activity but each time i want to import i've got an error message "blabla" isn't a valid classname (refId).
What am i suppose to put in these fields?

thanks for helping