asp.net - 400 Bad Request for OData -

i created .net 4.5 web project using visual studio 2012 test out using odata following this tutorial. however, whenever send following request fiddler:

put http://localhost:14116/odata/products(5) http/1.1 host: localhost:14116 accept: application/json content-type: application/json content-length: 67  { "name" : "apple //e", "price" : "1298", "category" : "computer" } 

i following response:

http/1.1 400 bad request cache-control: no-cache pragma: no-cache expires: -1 server: microsoft-iis/8.0 x-aspnet-version: 4.0.30319 x-sourcefiles: =?utf-8?b?yzpcdxnlcnnczgxhdmvsbgvczg9jdw1lbnrzxhzpc3vhbcbzdhvkaw8gmjaxmlxqcm9qzwn0c1xp    rgf0yvrlc3qzxe9eyxrhvgvzddncb2rhdgfcuhjvzhvjdhmonsk=?= x-powered-by: asp.net date: wed, 01 apr 2015 14:37:41 gmt content-length: 0 

what missing? (stack overflow removing 2 empty lines in http response.)

this request works fine:

get http://localhost:14116/odata/products?$filter=price+lt+500 http/1.1 host: localhost:14116 accept: application/json 

here's controller:

public class productscontroller : odatacontroller {     static list<product> s_products;     static productscontroller()     {         s_products = new list<product>();         s_products.add(             new product             {                 id = 1               , name = "nexus 7"               , price = 179               , category = "tablet"             }         );     }      // odata/products     [queryable]     public iqueryable<product> getproducts()     {         return s_products.asqueryable();     }      // odata/products(5)     [queryable]     public singleresult<product> getproduct([fromodatauri] int key)     {         return singleresult.create(s_products.asqueryable().where(product => product.id == key));     }      // put odata/products(5)     public ihttpactionresult put([fromodatauri] int key, product product)     {         if (!modelstate.isvalid)         {             return badrequest(modelstate);         }          if (key != product.id)         {             return badrequest();         }          var previous = s_products.singleordefault(p => p.id == key);         if (previous == null)         {             return notfound();         }          previous.category = product.category;         previous.name = product.name;         previous.price = product.price;          return updated(product);     }      // post odata/products     public ihttpactionresult post(product product)     {         if (!modelstate.isvalid)         {             return badrequest(modelstate);         }          s_products.add(product);          return created(product);     }      // patch odata/products(5)     [acceptverbs("patch", "merge")]     public ihttpactionresult patch([fromodatauri] int key, delta<product> patch)     {         if (!modelstate.isvalid)         {             return badrequest(modelstate);         }          product product = s_products.singleordefault(p => p.id == key);         if (product == null)         {             return notfound();         }         patch.patch(product);          return updated(product);     }      // delete odata/products(5)     public ihttpactionresult delete([fromodatauri] int key)     {         product product = s_products.singleordefault(p => p.id == key);         if (product == null)         {             return notfound();         }          s_products.remove(product);          return statuscode(httpstatuscode.nocontent);     }      protected override void dispose(bool disposing)     {         base.dispose(disposing);     } }