`void:triples` has page as subject instead of dataset.

[jeswr]

If we examine the response to https://rdf-play.rubensworks.net/#url=https%3A%2F%2Ffragments.dbpedia.org%2F2016-04%2Fen%3Fpage%3D2; it has the structure

<CONTROLS> {
	<CONTROLS> foaf:primaryTopic <FRAGMENT> .

	<DATASET>
		void:subset <FRAGMENT> ;
		hydra:search [...] ;
	.

	<FRAGMENT> void:subset <PAGE>.

	<PAGE>
		void:triples 1040358853 ;
		hydra:previous <PREVIOUS> ;
		hydra:next <NEXT> ;
	.
}

when really it should be

<CONTROLS> {
	<CONTROLS> foaf:primaryTopic <FRAGMENT> .

	<DATASET>
		void:subset <FRAGMENT> ;
		hydra:search [...] ;
		void:triples 1040358853 ;
	        hydra:totalItems 1040358853 .

	<FRAGMENT> void:subset <PAGE>.

	<PAGE>
		hydra:previous <PREVIOUS> ;
		hydra:next <NEXT> ;
	.
}

Discovered by @langsamu

[rubensworks]

I think it should even be:

<CONTROLS> {
	<CONTROLS> foaf:primaryTopic <FRAGMENT> .

	<DATASET>
		void:subset <FRAGMENT> ;
		hydra:search [...] .

	<FRAGMENT> void:subset <PAGE>;
		void:triples 1040358853 ;
	        hydra:totalItems 1040358853 .

	<PAGE>
		hydra:previous <PREVIOUS> ;
		hydra:next <NEXT> ;
	.
}

The spec says "In particular, it MUST contain a triple with a void:triples predicate that expresses the estimated total number of matches for the fragment's triple pattern. ".

I think Comunica supports both variants (but not the dataset variant).