I don't know if you are new to HP or to revenue sharing sites in general, but there is some fluctuation day to day, month to month. Sometimes it has to do with the writer's choice in topic, sometimes it has to do with the site itself, and sometimes there are external factors like holidays.
HubPages as a whole has experienced a decline in traffic, which is something that not everyone will tell you. Were I in your position just starting out, I would start testing various revenue sharing platforms to see which one gives you better traffic and higher earnings. Some of the most popular are
I do pretty well with Infobarrel, better than on Hubpages. Your results may vary, best of luck to you.