When click on Add New in the Site Wide Text Change plugin nothing happens

Hi:

Installed SWTC Plugin by coping file and folder per instructions in the mu-plugins as follows:

site-wide-text-change - goes in /wp-content/mu-plugins
/sitewidetextincludes/ - goes in /wp-content/mu-plugins

However, when Add New button is clicked nothing happens.

WPMU 2.8.4a

What I'm doing wrong?
Thanks.