I'm having trouble getting user registration working on WP multisite with the simplemodal-login plugin.
I think it's because I'm also using the domain forwarding technique so that two separate URLs exist under the same WP installation.
I've tried to edit the 'action' bit of the form using the instructions found on the simplemodal site, to no avail.
You can see the simplemodal bit of my theme's functions.php:
You can see I haven't changed much. The changes definitely appear in the production site, so that's not the problem.
The plugin doesn't have a descriptive error when it fails to register; it just says "ERROR" at the top and that's it. When it fails, no user is registered and no e-mail is sent.