The reason this is happening is because response.startswith('va') is always evaluating to false so #Do stuff here never gets executed.
First off, shouldn't it be message.text.startswith('va') or how is "response" created? Also, you may want to ensure that you're doing a case insensitive match so you might want to do a response.lower().startswith(...) however you are generating response.
Also, the word "response" somehow connotes that this is supposed to be the response that is sent when the message has been successfully processed.