Editing the Activity label does not change its name

i have changed the Activity type name by going to Administer CiviCRM > Option Groups > Activity Type Options and Editing the option and changing the label. i also changed the xml files in custom template. the new names displayed ok on search but did not on adding activity to the case. i went to database and saw that name field in civicrm_option_value table was not changed to new value just label field was. after i changed manually name to same value as label items started to appear. i am not sure is this an error that should be reported...