Not getting updated

Hi, I am new to linux. Today I installed COMODO AVL. It shows that “The virus signature database is not up to date. Update Now”. But when I try to update it, it shows the following error, though I have proper internet connection.

Failed to update the virus signature database.
Please check your internet connection and try again later.

I have gone through some of the earlier posts regarding this error, but I could not get any solution which works for me. I am sorry for the duplicate post.
Please help me. I am stuck with it.
Thanks in advance.