If you have this problem, try version 1.9.6 or higher and set the setting
"Disable CAPTCHA transparent text".
Note: If the CAPTCHA image is missing the text, go to the plugin settings and check the setting "Disable CAPTCHA transparent text". It will not fix it on the test page, but it might fix it on the wordpress forms.
== Changelog ==
= 1.9.6 =
- (31 Dec 2009) - New setting for a few people why had problems with the text transparency "Disable CAPTCHA transparent text (only if captcha text is missing on the image, try this)".
