the code 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=20&noisecolor=000000&noiseorder=behind&characters=5&charheight=&font=fonts/MOM_T___.TTF&textcolor=000000" alt="security code" width="200" height="50" />
also sets the name of the captcha session variable. this code passes a url variable named "field":
field=Security_Code_1
the value of the field variable is used in the captcha session variable name:
captcha_<field value>
so the name of the captcha session being created is:
captcha_Security_Code_1
In the server validation behavior, you are using the "captcha_Security_Code" session variable instead, you will need to edit the server validation and set the like entry validation to use the captcha_Security_Code_1 session variable.