SPARQL SELECT on different types

Hello,

I'm progressing nicely with my project in RoR, but I'm having a bit of trouble to fine tune the query needed to retrieve information about a specific city or town. I'm relying on DBPedia, and the two test cases are Manchester (in the UK) and OsnaBrück (in Germany)

The idea is to make the query as generic as possible, because it's constructred through Ruby on Rails, so I need to be able to replace the search values later on through variables. The Query i'm trying to tune is this one:

PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX prop: <http://dbpedia.org/property/>
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#type>

SELECT ?location ?abstract ?thumbnail 
WHERE 
{ 
  { 
    ?location foaf:label ?name .
    FILTER regex(?name, 'Osnabrück')
    ?location a dbo:Town .
  } 
  UNION 
  {  
    ?location a dbo:City;
              dbo:country <http://dbpedia.org/resource/Germany>
    { 
      ?location dbo:name ?name .
      FILTER regex(?name, 'Osnabrück') 
    } 
    UNION 
    {
       ?location foaf:name ?name .
       FILTER regex(?name, 'Osnabrück')
    }
  } 
  OPTIONAL { ?location dbo:thumbnail ?thumbnail . }
  OPTIONAL 
  {
    ?location dbo:abstract ?abstract . 
    FILTER langMatches(lang(?abstract), 'en')
  }
}

The idea behind the query is the following:

• I have a variable that holds the name of the location
• I have a variable that holds the URI of the country

I want to select any location that:

• Is either a dbo:City in a given Country
• With a specific name as foaf:name or dbo:name property
• OR is either a dbo:Town
• With a specific name as foaf:label

If I use the values 'Manchester' and <http://dbpedia.org/resource/United_Kingdom> I'm able to select the City of Manchester in the United Kingdom, but when I use the values 'Osnabrück' and <http://dbpedia.org/resource/Germany> I'm not able to select the town of Osnabrück, despite it having a page in dbpedia.

Could someone point out what I'm missing in my SPARQL query?