Why is it trying to use the bootstrap theme?

I am setting up simplenews to use its own theme for sending out HTML mail however whenever I clear the cache and try to send a test email I am getting the following:

Fatal error: Call to undefined function bootstrap_setting() in /home/site/public_html/sites/all/themes/bootstrap/templates/system/breadcrumb.vars.php on line 14

I have verified that all of the HTMLmail setting are using the Newsletter theme which is enabled but is not a bootstrap theme.

Suggestions on what to do?