Most people who view your work on FANBOX are people who are already your fans. Put another way, no matter how much effort you put into your activities on FANBOX, you often won't get noticed by people who aren't yet familiar with your work.
When you join FANBOX, you will probably find that your loyal fans generally join slowly, over time, and that the number of your supporters increases gradually. If you find that you aren't gaining many supporters, you may need to court fans in new markets.
If this happens to you, don't hesitate to use pixiv, Twitter, and other social media outside of FANBOX. By sharing your work and FANBOX activities on social media, you can get many more people interested in your work.