Problems with using KnowRob from Python

edit

I tried a python client to query from json_prolog, as the line below

query = prolog.query("owl_individual_of(A, knowrob:'SpatialThing')");

However, I got the following error message:

ERROR: An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line statement', (9, 0))
....

Edit: More info in response to question

Similarly, in the following code, the first query works and the second does not:

query = self.prolog.query("owl_subclass_of(A, knowrob:'FoodOrDrink').")
for sol in query.solutions():
    print 'Found solution. A = %s' %(sol['A'])

query = self.prolog.query("owl_has(A, rdf:type, knowrob:'Oven').")

Can anyone tell me where the error could be from? Did I miss anything?

The Prolog query works with rosprolog, but not json_prolog from python client.

Is there any working example of KnowRob in Python located somewhere by the way? The Java Client example won't compile.

Thanks.