I saw the new text and verified the folder is there.
Maybe the text could list what it's looking for.
I tried the snapshot so the files in that folder are:
\modules\org\jboss\as\server\main\jboss-as-server-7.1.0.Alpha1-SNAPSHOT.jar
\modules\org\jboss\as\server\main\jboss-as-server-7.1.0.Alpha1-SNAPSHOT.jar.index
\modules\org\jboss\as\server\main\module.xml
The one thing I did not try is putting the serve at the default location as shown in the dialog.