Overlay images not available for displaying
From semantic-mediawiki.org
Fragment of a discussion from Help talk:Gallery format
With no accessible public source available to inspect the issue and the format working on smw.org, there is yet little chance for making suggestions about the possible cause or solution.
The only advice I can give is to compare the examples on smw.org with the examples you have employed and check for possible JavaScript errors (see here).
PS: The change cited above for multilingual namespace support is only deployed with SMW/SRF 1.9.
