OK, that means that the captcha is failing validation.
in the server validation server behaivor, you have the like entry validation for captcha set to compare the "Registration_group_Security_code" form element against the "captcha_Registration_group_Security_code" session variable.
in the image tag that creates the captcha image:
<img id="capt1" src="webassist/captcha/wavt_captchasecurityimages.php?width=200&height=50&field=Security_Code_1&bgcolor=FFFFFF&transparent=0&bgimage=&gridfreq=20&gridcolor=000000&gridorder=behind&noisefreq=17&noisecolor=000000&noiseorder=behind&characters=5&charheight=&font=fonts/MOM_T___.TTF&textcolor=000000" alt="security code" width="200" height="50" />
one of the variables that is passed is name d"field:
the captcha session name is created as "captcha_<field value>" so the session variable you should be using is named "captcha_Security_Code_1".
you will need to edit the like entry server validation to compare the "Registration_group_Security_code" form element against the "captcha_Security_Code_1" session variable