I am attempting to use KeePass (v. 2.20.1) with Chrome (v. 25.0.1364.5 dev-m).
Running WinXP SP3.
It appeared to be working one time with the KeePass icon appearing to the browser URL bar, but subsequent to this instance, no joy.
Chrome indicates ChromeiPass is interacting and KeePass (Tools-Plugins) shows KeePassHttp (v. 188.8.131.52) loaded.
To get it to work the first time, I had to utilize KeePassHttp.dll and Newtonsoft.Json.dll. Dropping KeePassHttp.plgx into the KeePass.exe directory did nothing.
Did you follow the instructions here?