Always incorrect Anti-Splog reCAPTCHA


First of all, I couldn't find the Anti-Splog plugin in the list of plugin, so I just selected a somewhat random plugin instead. Feel free to re-tag/move my post to the Anti-Splog forum (if there is one).

I'm having issues with the Anti-Splog plugin on my WordPress Multisite network.

It seems like the reCaptcha part of the Anti-Splog is impossible to solve. It returns "The reCAPTCHA wasn't entered correctly. Please try again.", no matter what the users type in the text field.

The reCaptcha used to work fine just a few weeks ago, and I've got no clue what change that made it stop working.

The WPMU API key has been accepted (it has a green background color). Both the public and the private reCaptcha keys are correct.

Does anyone have a clue what the cause of this problem could be?