Hi.
I sent you a message but have not received a reply so I thought I may better contact you here.
Sweet Captcha works just fine but not on the cell phone or Samsung tablet. I am using it to login for admin but on the tablet I can't log in. I have to deactivate this for the login which is a bummer, frankly.
Please let me know if there will be a fix for this.
http://wordpress.org/extend/plugins/sweetcaptcha-revolutionary-free-captcha-service/