Menu does not appear

Hello all - I'm pretty new here and just purchased Hot Flashes Menu. I installed the module, gave it a position, created a new menu and loaded the position into an article - so far so good, nothing visible without menuitems. As soon as I add menuitems to the hotflashmenu, I get this error:

Fatal error: Call to undefined function artxTagBuilder() in /home/cshop/diraction.ch/www/templates/da_template_white/html/mod_menu/default_component.php on line 37

Any suggestions what I did wrong? Thank you very much for every help!

that error comes from your template , that has default joomla menu overload:
templates/da_template_white/html/mod_menu/default_component.php

You can simply rename folder mod_menu to mod_menu_ to disable that overload, but that can affect other menus if specific for that template, you can try an turn it back if no good, otherwise contact template provider.