Can't choose calendar for new events in ical on iphone

For a while now my iPhone 4 (current software) has not allowed me to choose which calendar in which to place new events. I am positive this is a feature I had, and very much used. Why isn't my phone letting me choose between calendars for new events and how can I fix it? I have all the calendars synced, and they are all selected and displaying events on my iPhone. I can only select between calendars for new events on my computer, though.

Thank you!