Cookies toolkit 2.1 is not compatible with Dreamweaver CS4 Or Dreamweaver CS5.
I believe the last version of Dreamweaver that Cookies Toolkit v2 was compatible with would have been Dreamweaver MX2004 or 8. To use cookies toolkit in Dreamweaver CS4 or CS5, you would need to purchase an upgrade to Cookies Toolkit version 3, Contact our sales department at sales[at]webassist[dot]com for details.