Jena Fuseki ontology accepted but not viewable - webserver

Question

So we are supposed to set up a "web Server" ontology on fuseki and access it via nodejs.
I created the dataset "data" and added my ontology via xml. Fuseki accepted it . This is the ontology :
<?xml version="1.0" encoding="utf-8" ?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns:owl="http://www.w3.org/2002/07/owl#"
xmlns:rdfs="http://www.w3.org/2000/01/rdf-schema#"
xmlns:ns0="http://localhost:3000/data#">
<owl:DatatypeProperty rdf:about="http://localhost:3000/data#message">
</owl:DatatypeProperty>
<owl:DatatypeProperty rdf:about="http://localhost:3000/data#firstname">
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#ObjectProperty"/>
</owl:DatatypeProperty>
<owl:DatatypeProperty rdf:about="http://localhost:3000/data#lastname">
<rdf:type rdf:resource="http://www.w3.org/2002/07/owl#ObjectProperty"/>
</owl:DatatypeProperty>
<owl:Class rdf:about="http://localhost:3000/data#linkeddata">
<rdfs:comment>The class of all data types.</rdfs:comment>
<rdfs:label>The data type</rdfs:label>
</owl:Class>
<owl:Class rdf:about="http://localhost:3000/data#users">
<rdfs:comment>Users that post Tweets.</rdfs:comment>
<rdfs:label>Users</rdfs:label>
<rdfs:subClassOf rdf:resource="http://localhost:3000/data#linkeddata"/>
</owl:Class>
<owl:Class rdf:about="http://localhost:3000/data#tweets">
<rdfs:comment>Tweets contain messages of Users.</rdfs:comment>
<rdfs:label>Tweets</rdfs:label>
<rdfs:subClassOf rdf:resource="http://localhost:3000/data#linkeddata"/>
</owl:Class>
<owl:ObjectProperty rdf:about="http://localhost:3000/data#tweetedby">
</owl:ObjectProperty>
<rdf:Description rdf:about="http://localhost:3000/data#1234">
<rdf:type rdf:resource="http://localhost:3000/data#tweets"/>
<ns0:message>blablubbtweet</ns0:message>
<ns0:tweetedby>
<ns0:users rdf:about="http://localhost:3000/data#2345">
<ns0:firstname>Manuel</ns0:firstname>
<ns0:lastname>Neuer</ns0:lastname>
</ns0:users>
</ns0:tweetedby>
</rdf:Description>
</rdf:RDF>
I hope you can see that I created the classes "users" , "tweets" and "linkeddata" .
If I try view the data on the Fuseki server with the endpoint "/data/query" with following code its says "no data in table". Im expecting 27 Triples...what am I overlooking ?
prefix owl: <http://www.w3.org/2002/07/owl#>
prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?class ?label ?description
WHERE {
?class a owl:class.
OPTIONAL { ?class rdfs:label ?label}
OPTIONAL { ?class rdfs:comment ?description}
}