irules for different pool

You first have to understand all of the parts of a URL. So for example:

http://www.domain.com/images/mycat.png?foo=bartest

www.domain.com is the host, so that's accessible with the [HTTP::host] or [HTTP::header Host] command

/images/mycat.png?foo=bar is the "URI", so that's accessible via the [HTTP::uri] command

/images/mycat.png is the path, so that's accessible via the [HTTP::path] command

?foo=bar is the query, so that's accessible via [HTTP::query]

So to answer your question, "login.txhd.com" isn't matching your [HTTP::uri] match because "login" isn't in the URI, it's in the Host.