[dotNetRDF-Support] NamespaceMapper doesn't find prefix

[Frank S. <fs...@in...>]

Hi folks,

I have strange problem with the IGraph.ExecuteQuery(string s) method. 
For the following query-string:

SELECT * where { ?releaseGroupURI a mbo:ReleaseGroup. ?releaseGroupURI 
mbo:musicBrainzId ?mbId. FILTER (REGEX(STR(?mbId), 
"c9744809-c5b8-4d3c-a115-1a3daa881c09", "i")). OPTIONAL 
{?releaseGroupURI rdfs:comment ?comment} }

I get the following error:

{"The Namespace URI for the given Prefix 'mbo' is not known by the 
in-scope NamespaceMapper.  Did you forget to define a namespace for this 
prefix?"}

But I DID defined the prefix beforehand:
graph.NamespaceMap.AddNamespace("mbo", new 
Uri("http://creativeartefact.org/ontology/"));

I double checked it in the local variable window of my Visual Studio and 
also entered the line

graph.NamespaceMap.GetNamespaceUri("mbo");

in the direct window, which yields the expected result.

If I add "PREFIX mbo: <http://creativeartefact.org/ontology/> " in front 
of my query, everything works fine.

Any idea, why the NamespaceMapper doesn't find the defined prefix(es - 
same with rdfs.)?


Thanks in advance,
Frank


-- 
************************************************
* Universität Leipzig, Institut für Informatik *
*  Abteilung Betriebliche Informationssysteme  *
*     http://bis.informatik.uni-leipzig.de     *
*            Tel.: 0341 / 97 32 256            *
*                                              *
* ========== Opera Metal: molllust =========== *
*           http://www.molllust.com            *
*          M'era Luna Newcomer 2013!           *
************************************************