Hi

I have the following Json :

"{\"doc\":{\"info\":{\"allowDistribution\":\"true\",\"allowSearch\":\"true\",\"calaisRequestID\":\"67a02f61-7e45-cfc4-1276-e123c5f7422f\",\"externalID\":\"\",\"id\":\"http://id.opencalais.com/dBo1YRiQeqS-kfO-m9UeWA\",\"docId\":\"http://d.opencalais.com/dochash-1/8edabb36-eece-3f67-b187-ab64cd885ecb\",\"document\":\"What type of music do you listen to? How much would you pay for a cd? Do you still buy cds? Do you like Shakira? What genre of music do you listen to?\",\"docTitle\":\"\",\"docDate\":\"2010-03-17 17:40:41.323\",\"externalMetadata\":\"\",\"submitter\":\"\"},\"meta\":{\"contentType\":\"text/raw\",\"emVer\":\"7.1.1103.5\",\"langIdVer\":\"DefaultLangId\",\"processingVer\":\"CalaisJob01\",\"submitionDate\":\"2010-03-17 17:40:41.183\",\"submitterCode\":\"b54c734e-b865-185b-c83a-66e1c66272de\",\"signature\":\"digestalg-1|FXnvwLovOsqVoSPX0JfGvj3tp7s=|cyV2tZWY9OXG1RBO0SuND4kd3Pkvqv0cS2YpsEBQhXDfSV4KoE61sQ==\",\"language\":\"English\",\"messages\":[]}},\"http://d.opencalais.com/dochash-1/8edabb36-eece-3f67-b187-ab64cd885ecb/cat/1\":{\"_typeGroup\":\"topics\",\"category\":\"http://d.opencalais.com/cat/Calais/EntertainmentCulture\",\"classifierName\":\"Calais\",\"categoryName\":\"Entertainment_Culture\",\"score\":1},\"http://d.opencalais.com/dochash-1/8edabb36-eece-3f67-b187-ab64cd885ecb/cat/2\":{\"_typeGroup\":\"topics\",\"category\":\"http://d.opencalais.com/cat/Calais/HumanInterest\",\"classifierName\":\"Calais\",\"categoryName\":\"Human Interest\",\"score\":1},\"http://d.opencalais.com/dochash-1/8edabb36-eece-3f67-b187-ab64cd885ecb/cat/3\":{\"_typeGroup\":\"topics\",\"category\":\"http://d.opencalais.com/cat/Calais/TechnologyInternet\",\"classifierName\":\"Calais\",\"categoryName\":\"Technology_Internet\",\"score\":0.932}}"

Can you please tell me why it won't parse this?

This is my code:

JObject o = JObject.Parse(json);
String category = (string)o["doc"]["_typeGroup"]["categoryName"];

It tells me:

Object reference not set to an instance of an object.

Thanks :)