You don’t mention which version of MS Outlook you use ?
This provider is for MS Outlook (not express), so if you are using MS Outlook:

Make sure the avast plugin is not disabled in MS Outlook:
Outlook 2007 > Tools > Trust center > Add-inns > Manage Disabled items.
Outlook 2003 > Help > About > Disabled items
Outlook 2000 > Tools menu > Options > Other > Advanced Options > Add-In Manager.