have you run the install script on the server yet?
It almost seams like you ran the install script locally, then uploaded the gallery files to the server, but have not run the installer on the server.
The line that is reporting the error is associated to code that populates the wa_settings array from the wa_settings table from the database, if the installer script has not been run on the remote server, this table wont exist yet.
if you haven't run the install script on the server yet, delete the connections/installed.txt file so the install script will run.