These are the instructions found on your profile page
To display a custom avatar go to gravatar.com and upload an image for the email address associated your able2know account. Changes will be reflected as gravatar.com caches and your browser cache is cleared. This can take anywhere from minutes to hours typically. Users with no custom gravatar have a unique image generated to help others distinguish between posts. Avatar sizes can be changed in your preferences or avatars can be turned off altogether.
The problem may be that you are using an image file that is not a compatible format. Please either post a link to the image on the internet or type in the file name you uploaded for your avatar.
That will tell us if it is a good format.
Also check the content rating you gave it over at gravatar.com. if it isnt for general audiences, change it.
If it still doesn't display correctly, try using a different image.