c# - NotSupportedException when doing a Bing image search programatically -

i using following code more 50 results bing image search using bing search container bing api. problem when try , execute query (query.excecute()) after changing off-set next 50 results ("$skip", 50) following error:

a first chance exception of type 'system.notsupportedexception' occurred in microsoft.data.services.client.dll

i can't figure out how query. re-iterate occurs when when loop executes second time. happens on line var results = query.execute(); , when tries query.

   void bingsearch(string searchterm)         {             try             {                 imageset = new list<bing.imageresult>();                 const string bingkey = "[key]";                 var bing = new bingsearchcontainer(                 new uri("https://api.datamarket.azure.com/bing/search/")) { credentials = new networkcredential(bingkey, bingkey) };                                 var query = bing.image("\"" + searchterm + "\"" + "(" + site1 + ")", null, null, null, null, null, imagefilters);                 debug.print("full search: " + query.tostring());                 int length = 3;                 int resultspage = 0;                  (int = 0; < length; i++)                 {                     query = query.addqueryoption("$top", 50);                     query = query.addqueryoption("$skip", resultspage);                     var results = query.execute();                     int index = 0;                     foreach (var result in results)                     {                         imageset.add(result);                         debug.print("url: " + imageset[index].title);                         index++;                     }                     resultspage = resultspage + 50;                     debug.print("getting next page: " + resultspage);                }                 debug.print("results: " + imageset.count);             }             catch             {                 debug.print("error");             }         }