Newsletter Problem

[Guest]

I have just tried to create a test newsletter to myself to test if html is being sent. I left Newsletter selected as default in the drop down box, I entered a title then I entered my content, then I clicked 'Save' and recieved the following error at the top of the page:

 

Error: Newsletter module required

 

What's going on? I checked admin/includes/modules/newsletters/ and newsletter.php is there and then only modification I have made is to change

 

$mimemessage->add_text($this->content);

 

To

 

$mimemessage->add_html($this->content);

 

after seeing this tip in another thread in this forum.