[Plugin: Custom Post Type UI] custom post type archive page not working

I have just struggled with a problem and thought I would post the solution in order to help anyone else who has googled this phrase and NOT found a solution.

I used the Custom Post Type UI plugin to create custom post types and then used tutorial code I found in other websites to create a custom post type archive page. (eg: archive-custom.php)

And the archive page would simply not work. WordPress didn’t seem to know it existed, even though it was in the right place and had good code.

The reason is that WordPress DIDN’T know it existed, because I failed to know about the “has archive” setting in the advanced options section of the Custom Post Type UI plugin.

This is set to FALSE by default (for what reason, I cannot say), but it must be set to TRUE in order for the archive page to be recognized.

There is an AWFUL lot to keep track of with this stuff. Just thought you might like to know.

http://wordpress.org/extend/plugins/custom-post-type-ui/