RDFx error on display VARQL view

Hello Remon,

first of all thanks for the project and the nice introduction with an example. That helped me getting started and playing around a little bit. I follow your example steps and after I've created the new view and add a Page display I get the following error message.

Notice: Undefined index: store_read_key in rdfx_arc2_init_remote_store() (line 171 of drupal\sites\all\modules\rdfx\rdfx.sparql.inc).

Has the error something to do with VARQL? Did you have any idea what's going wrong?

Thanks.