Custom Taxonomy

I purchased this plug in recently and have set up a custom content type with a custom taxonomy. When I add a new post to my custom type the custom taxonomies show up, but I cannot "check" / select a category. They boxes are greyed out. I think I have all the permissions set right so that I (the admin) have rights to set the categories in my taxonomy, but something isn't working right. Please help, thanks.

Jess