yep, you can try again on july 11th! since you have the remainder of this week, i'd keep trying periodically in case someone makes changes.
if you don't get into them right away, put SOMETHING there so that you're at least fully registered.
if all else fails and it's a course you must have in order to get into your 2nd year major, you can always talk to an academic advisor. if you're not able to physically go in and talk to them, you can email them (see main social science webpage). it might take a couple of days for them to reply because it's so busy right now, but they do respond.
[email protected]