Requirements
Must return id and label
Example
Test with the following.
SPARQL
#Cats
SELECT ?id ?idLabel (?idLabel as ?label)
WHERE
{
?id wdt:P31 wd:Q146. # Must be a cat
SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],mul,en". } # Helps get the label in your language, if not, then default for all languages, then en language
}