When an element of a map is in maintenance you cannot select this map from monitoring -> maps.
This seems to be a return of the issue in
ZBX-1605. The same error is logged in the apache logs:
[Wed Feb 19 13:10:59 2014] [error] [client ********] PHP Fatal error: Call to undefined function get_maintenance_by_maintenanceid() in /usr/share/zabbix/include/maps.inc.php on line 1248
Workaround is to add require_once('include/maintenances.inc.php'); to include/maps.inc.php ;
The map can still be edited, just not displayed.