fopen()

Hi ,
I am getting an error when enabling the module on drupal 6.7:

    * warning: fopen(sites/default/filesmin.js) [function.fopen]: failed to open stream: Permission denied in /home/content/h/o/f/hofitgabo/html/sites/all/modules/javascript_aggregator/javascript_aggregator.module on line 47.
    * warning: fclose(): supplied argument is not a valid stream resource in /home/content/h/o/f/hofitgabo/html/sites/all/modules/javascript_aggregator/javascript_aggregator.module on line 49.

why is it asking for the filesmin.js file ?

thanks in advance
yaniv nizry
www.guzzus.com