Events+ RSS feed showing expired events

I am trying to create an upcoming events feed to display our events on another site. I am using this url right now: http://boomboxoffice.ca/feed/?post_type=incsub_event&event_year=2014&event_monthnum=8
But it is only displaying a couple of events that happened at the beginning of the month. It would be great if it could show a list starting at today and looking ahead past the end of the month. Are there any other variables I could pass to make that happen?