Error code when no conditions match in iRule

Would this work for you?

ltm rule /Common/test1_iRule {
    when RULE_INIT {
        log local0. "------------------------------ INIT ------------------------------------"
    }

    when XML_CONTENT_BASED_ROUTING {
        set ValueFound 0
        set RoutingInfo "0"
        for {set i 0} { $i < $XML_count } {incr i} {
             Routing by RoutingLabel
            log local0. "XML_queries $XML_queries($i)" 
            log local0. "XML_values $XML_values($i)" 
            if { ($XML_queries($i) contains "RoutingLabel")} {
                if { ($XML_values($i) eq "test1")} {
                   pool test1_p
                   set RoutingInfo "test1"
                   set ValueFound 1
                   break
                } elseif {($XML_values($i) eq "test1_encr")} {
                   pool test1_encr_p
                   set ValueFound 1
                   set RoutingInfo "test1_encr"
                   break
                } elseif {($XML_values($i) contains "SOAPtest")} {
                   pool test1_sim_p
                   set RoutingInfo "SOAPtest"
                   set ValueFound 1
                   break
                } elseif {($XML_values($i) contains "test2")} {
                   pool test2_p
                   set ValueFound 1
                   set RoutingInfo "test2"
                   break
                }
            }
        }
        log local0. "RoutingInfo is $RoutingInfo after selecting pools"
    }

    when LB_FAILED {
        if { $ValueFound == 0 } {
             HTTP::respond 422 Connection close
        }
   }
}

?