Query builder is a very old extesnion that has been discontinued and is not compatible with Dreamweaver CS4.
The version of Query Builder you have installed, 2.5.5, was released in 3/2005.
In 5/2005 it was upgraded to Database Search.
in 10/2007, DataAssist 2 was released which included Database search.
The latest version of Dreamweaver that you could use Query Builder in would me Dreamweaver MX 2004.
You would need to upgrade to DataAssist 2 to get the same functionality in Dreamweaver CS4.