Gmap not working for me

This is the first time I have posted an issue and hope that I am doing it in the right way.

My problem is I can't get off the starting line with Gmap. It looks like it could be a great feature for my site but when I turn on the Gmap modules I keep getting this error message (see below).

user warning: Unknown column 'eid' in 'where clause' query: SELECT latitude,longitude FROM location WHERE eid = 0 AND type='user' in /var/www/vhosts/ad-mad.co.uk/httpdocs/includes/database.mysql.inc on line 172.