Completion Status

I am building a course which doesn't have an end assessment. I simply wish the course to complete when the learner reaches the last page.I created an action on the final page which sets the "AICC_Lesson_Status" variable to "completed" (as suggest by my LMS provider), on SHOW (eg when the user final page loads). The course has been loaded to the LMS but when I get to the final page, I now get the error message "Incorrect data type". Do you have any idea what this error message means?Thank you for any help!