Not working on multisite

I have wordpress configured in multisite mode with three sites. One is the primary site, and the calendar plugin appears to work fine there. But on the other two sites, the calendar plugin is broken. None of the javascript features appear to be working. If I click the date & time fields when trying to add an event, nothing pops up. If I try to click any of the boxes below (such as location), nothing happens.

Additionally, error messages appear in the event box when on the “add event” page:

Warning: http_build_query() [function.http-build-query]: Parameter 1 expected to be Array or Object. Incorrect value given in /path/to/site/wp-includes/Requests/Transport/cURL.php on line 508

Additionally, the plugin settings page has no settings displayed on the two multisite sites.