Help with i-rule

use this code:

when HTTP_REQUEST { 
    if {[string tolower [HTTP::uri]] starts_with "/helloworld"} { 
        pool pool_www.abc.com_HelloWorld 
    } else{
        pool pool_www.abc.com_default
    }
}

when you use $1, it means you convert the uri to lowercase... if you compare to /HelloWorld, it will always fail because it contains uppercase.