Error when trying to add a new variant to node-view

Hello,

I am receiving an error when trying to add a new vaiant to node-view.

Status message

Before this variant can be added, it must be configured. When you are finished, click "Create variant" at the end of this wizard to add this to your page.

Error message

Error: Call to undefined function entity_type_supports() in flag_flag_is_flagged_access_get_children() (line 33 of /home3/sitedirectory/public_html/thesitename/sites/all/modules/flag/plugins/access/flag_is_flagged/flag_is_flagged.inc).

The website encountered an unexpected error. Please try again later.

Please advise,
Thanks!