[TYPO3] Help on Mailform Captcha Extension (cr_tmailform_captcha)

[tonix (Antonio Nati)]

I'm setting up this extension, and it apparently works, but no 
checkin done on the typed field.

I've loaded these extensions:
	- Tmailform (pil_mailform)
	- sr_freecap
	- Mailform Captcha Extension (cr_tmailform_captcha)

tmailform works fine, and after adding

<!-- ###CAPTCHA_INSERT### -->
         ###SR_FREECAP_NOTICE###
         ###CAPTCHA_ERR_TXT###
         <input type="text" size="15" 
name="tx_pilmailform_pi1[text][captcha]" value="" />
         ###SR_FREECAP_IMAGE###
<!-- ###CAPTCHA_INSERT### -->

the image with a fuzzy image appears, but form is sent despite of any 
wrong value typed in the captcha field.

Any hint on what can be the problem?
Is there any suggestion/example/configuration which may be shown?

Thanks,

Tonino