Irule Issue - url rewrite and redirect

so can i try as below

Code
when HTTP_REQUEST {
log local0. "Original path: [HTTP::path]"
log local0. "Original uri: [HTTP::uri]"
if { [HTTP::uri] starts_with "/db/ap-webconsole" }{ 
HTTP::host "[HTTP::host]:3333"
HTTP::path [string map {/db/ap-webconsole /ap-webconsole} [HTTP::path]]
log local0. "Pool app1 chosen" 
pool app1 
log local0. "Modified uri: [HTTP::uri]"     }
else {
log local0. "Pool app2 chosen" 
 pool app2
}
}

still i am getting error on line 5 , how we can modify the host with :3333 or use respond location 301 because backend http host is change to something else do i required to modify the response as well with stream profile ? pls assist