Unable to delete Roles created in OIM

I created two Roles in OIM using the OIM UI. After seeing that they were directed to the wrong container in our OID, I tried to delete these two Roles using the OIM UI, but I am unable to do so. I sign into OIM as xelsysadm, choose Roles from the Search drop-down list, then click on the Search button, select one of these two Roles in the search results list, and click on the Delete Role button. In response, I get a message dialog with a message of "Unknown error" and a window title of "Error Message".
Both Roles were created by xelsysadm, which has the role of ROLE ADMINISTRATOR. I'm using OIM 11.1.1.5.0 connected to OID 11g.