I'm trying to create some JavaScript that will identify two matching drop down lists and send a pop-up alert. The alert would state "You must select one schedule per rank.". It would be nice to have it prevent the user from submitting the form if duplicate schedules are chosen but not a requirement.

I attempted to use various JavaScript snippets using the developer tools in IE10 but just something as simple as creating an alert on drop down change wouldn't work according to the editor:

I'm not sure what I'm doing wrong and I'm not sure where to even begin with finding duplicates in the drop down lists.