posting results from off-line conversation/e-mails - looks like Laura is using 1.6 Choice code, possibly inside a 1.5.3 install.
Laura - try going to the admin page of your site - a database upgrade script might run which might fix your problem.
-if the script doesn't run, check the database structure of the choice table. - if a field named "release" exists, you will need to change it to "showresults"
you can do this by running this sql command on your db.
ALTER TABLE mdl_choice CHANGE `release` showresults tinyint(2)
unsigned not null default '0';