Sparql insert data not working

I'm a newbie to Sparql, but I am unable even to make a simple insert data query, or so it seems.

I'm using Apache Fuseki as working server; I'm in a graph, and I'm trying to make this query work:

PREFIX oa: <http://ift.tt/1FdgyHl;
PREFIX rdfs: <http://ift.tt/1cmhdKn;

INSERT DATA{             
  [ a 
    oa:Annotation ;                    
    rdfs:label "Title";                    
  ] .                    
}

But it doesn't matter what I do, I keep getting this error:

Error 400: SPARQL Query: No 'query=' parameter

This is even a semplified code, I tried many queries even more complex, but the result doesn't change...

via Chebli Mohamed