Hello Jeniffer,
Thanks for answering. In fact if you have both layers in the same map it will work. But if you have just the GraphicsLayer, it won't. I'm attaching a sample. It has two layers (a GraphicsLayer and one ArcGISTiledMapServiceLayer). The ArcGISTiledMapServiceLayer is commented. It references the API version 2.4. If you run and use the measure tool, it'll fail.
Now, uncomment the ArcGISTiledMapServiceLayer and it will work. Even if you set this layer as invisible. And if you change the references (use the API version 2.2 BETA or 2.0, par exemple), it will work even if the ArcGISTiledMapServiceLayer is commented.
Thank you,
André