Graphx Scala Vertices alwayses return me 0 - scala

Question

I'm tring to implement this Graphx example:
import org.apache.spark._
import org.apache.spark.graphx._
val conf = new SparkConf().setAppName("GraphX Example")
val sc = new SparkContext(conf)
// Create an RDD of vertices
val verticesRDD = sc.parallelize(Seq((-1L, "nowhere"), (1L, "yahou"), (2L, "sanae"), (3L, "hanane"), (4L, "said"), (5L, "halima")))
// Create an RDD of edges
val edgesRDD = sc.parallelize(Seq(Edge(1L, 3L, "commenter"), Edge(1L, 3L, "suivre"), Edge(2L, 3L, "commenter"), Edge(2L, 5L, "connecter"), Edge(4L, 2L, "connecter")))
// Create the graph with the default vertex
val graph = Graph(verticesRDD, edgesRDD, "nowhere")
graph.vertices.collect.foreach(println)
graph.edges.collect.foreach(println)
val numVertices = graph.numVertices
val numEdges = graph.numEdges
println(s"Number of vertices: $numVertices")
println(s"Number of edges: $numEdges")
and it returns me always 0 on $numVertices
it doesn't seem that something is wrong
PS: In my example i expect the result to be 6

Answer 1

The issue finally was with:
val conf = new SparkConf(). setAppName("GraphX Example") val sc = new SparkContext(conf)
so when i use it two times in a spark-shell it shutdowns automaticlly
the solution is that i restart my machine and rexecute the script without these two lines and it worked, thank you all