How can control the score for this drag and drop?

I am putting together a few games to compliment a training resource from a client. One of the games is a pretty simple drag and drop. The score adjusts automatically as the items are sorted into the correct (+10) or incorrect (-5) category. I like that learners don't have to click submit and that they see real-time scoring telling them exactly which items are correct or incorrect.

The issue: technically you can keep dragging and dropping either right or wrong answers and run the score up or down. I would like for the sorted items to be disabled after they are sorted into the correct category so that they stayed put and the score could not be manipulated. I attempted to trigger a disabled state once the answers were dropped onto the correct item, but this didn't work and messed up the scoring system and the disabled state never displayed.

Additionally, it is annoying that if the learner grabs an item to sort and then lets go of it while not over any categories, it turns to the incorrect state and takes away 5 points. I would like to fix this as well.

Any ideas or suggestions to try here? I've included the file.

Thanks so much,

Carrie

[View:http://community.articulate.com/cfs-file.ashx/__key/CommunityServer.Discussions.Components.Files/65/5023.ScreenShotDragAndDrop.tiff:650:0]