I've just changed the config file to run in debug mode and I see this
Error (1146): Table 'website.cms_module_news_fieldvals' doesn't exist
My table has no prefix and is callled
website.module_news_fieldvals
Having looked at the action.default.php I can see an error on line 280.
//
// Handle the custom fields
//
$query3 = 'SELECT A.value,B.id,B.name,B.type FROM cms_module_news_fieldvals A, cms_module_news_fielddefs B WHERE A.fielddef_id = B.id AND B.public = 1 AND A.news_id = ? ORDER BY B.item_order';
I've changed it to:
//
// Handle the custom fields
//
$query3 = 'SELECT A.value,B.id,B.name,B.type FROM '.cms_db_prefix().'module_news_fieldvals A, '.cms_db_prefix().'module_news_fielddefs B WHERE A.fielddef_id = B.id AND B.public = 1 AND A.news_id = ? ORDER BY B.item_order';
and all is now working.
Hope this helps someone else.
Thanks for your replies.