Recaptcha problem in coldufsion

tried the recaptcha.cfm but since I'm a newbie I think I must have
made something in the wrong way or maybe I missed somehting that is
obvious

When I execute the page

I get the following error:
Error Occurred While Processing Request
Cannot find CFML template for custom tag recaptcha.
ColdFusion attempted looking in the tree of installed custom tags but
did not find a custom tag with this name. If you are using per-
application custom tag mappings, ensure that per-application settings
are enabled by the administrator.

The error occurred in D:\wwwroot\gardenpassion.cfdeveloper.co.uk
\wwwroot\Identify\recaptcha2.cfm: line 7

5 : <cfform>
6 :
7 : <cf_recaptcha
8 : privateKey="my_private_key"
9 : publicKey="my_public_key">

hum ?