Problem with geofield

Hi,
i've a problem with editing of geofield_formatter_map and geofield_widget_map.
In editing and in field setting of content type I receive this error:

Exception: Projection 900913 lacks an authority code. Read http://drupal.org/node/1944074 for hints. in openlayers_get_projection_by_identifier() (linea 996 di ~/sites/all/modules/openlayers/openlayers.module).

What can I do?

thanks