Blogs widget and avatars plugin issues at WP 3.0

Hi,
I wanted to add a blog widget but instead of a widget appeared the fatal error:
"Call to undefined function get_blog_avatar() ..."
As I noticed - this function is in Avatars plugin (btw: there's no information about it in the installation guide).
But when I install Avatars plugin - I've got 6 plugins available in my control panel:

Avatars Version 3.4.0 | By Andrew Billits (Incsub)
Avatars Version 3.4.1 | By Andrew Billits (Incsub)
Avatars (BBPress) Version 3.4.0 | By Andrew Billits (Incsub)
Avatars (Comments) Version 3.4.0 | By Andrew Billits (Incsub)
Avatars (Posts) Version 3.4.0 | By Andrew Billits (Incsub)
Avatars (Widget) Version 3.4.0 | By Andrew Billits (Incsub)

When I activate Avatars plugin (Version 3.4.0 or 3.4.1) the fatal error appears:
"Cannot redeclare get_avatar() (previously declared in /wp-includes/pluggable.php:1598)"

The rest of the plugins (BBPress, Comments, etc.) have been installed correctly, but a blog widget still doesn't work.

As I noticed - those plugins are compatible with WP 3.0, aren’t they ?

Can you please explain why they are not working then?