[GeoNetwork-users] add raster record to geonetwork

hello every one.
i'd like to connect raster file from postgresql to geonetwork (iso19139)
but in the resolution section has error

\ncvc-datatype-valid.1.2.3: '' is not a valid value of union type
'UomIdentifier'. (Element: gco:Measure with parent element:
gmd:resolution)\ncvc-attribute.3: The value '' of attribute 'uom' on
element 'gco:Measure' is not valid with respect to its type,
'UomIdentifier'. (Element: gco:Measure with parent element: gmd:resolution)

every body know how handle it

best regards
hosein