Citazione:
We think your server is running the Apache web server.
The rewrite test failed and the most likely cause is that AllowOverride is not set to All for Elgg's directory. This prevents Apache from processing the .htaccess file which contains the rewrite rules.
A less likely cause is Apache is configured with an alias for your Elgg directory and you need to set the RewriteBase in your .htaccess. There are further instructions in the .htaccess file in your Elgg directory.
Quindi prima di perdere tempo inutile a cercare come risolvere il problema volevo sapere se il serve altervista supporta Elgg.