This is "sales'. This is "recruiting". You are a recruiter on the internet. Sales is all numbers. Every product, every business recruits based on statistics. Internet statistics are up for grabs. You need a lot of traffic to get "recruits".
In sales it takes seven contacts to make one appointment. How many times have your visitors visited your hub? Have any of them visited at least seven times or have 10 of them visited an average of 7 times? Then you have a chance at recruiting.
Do they know why they should sign up for Hubpages? Maybe from their point of view they didn't see anything that "grabbed" them.