I do not think you linked our adsense account properly. Go to
"My Account" and click "Earnings" then click "Affiliate Settings"
Now on that page, Google Adsense should be listed. Click "Configure" and make sure you entered the right ID for your adsense. It should be something like this: ca-pub-7305206719100795
Make sure that next to where it says Google Adsense, it says "Active" and that you have approved Hubpages to access your Google Adsense from your gmail account.
if you have done all that above and it is still not working, try these pages:
if none of the things I stated above are helping you then it is time you contacted the Hubpages team for specialized help. I hope this helps answer your question.