You are only taking the value of CommunityID from the response.
I don't see the code where you get your SESSIONID cookie.
You must fetch that cookie and provide it in the next calls to the service.

The docs for HTTP::Cookies says it can be accomplished this way:

$cookie_jar->extract_cookies( $response )
[download]

After getting the cookies, you set them on SOAP::Transport::HTTP

$soap->transport->cookie_jar($cookies);
[download]

Now you can make more calls on the service.

Update: re-read the doc with more attention, and the cookie_jar should handle the cookies.