Captcha image not showing

I'm trying to log into the setting page and can't get the captcha image to show. I tried to give "write" rights for several different accounts but it still doesn't work, what am I doing wrong?

Sorry I didn't understand how the settings page is related to Captcha? And write rights too... not really clear what do you mean.

Refer to this Captcha add-on discussion thread, maybe there you will find an answer... or just re-post there your problem, forming the question in the appropriate way.