Unauthorized error in KeywordQuery search object SP2013

Question

I am getting UnauthorizedAccessException while creating KeywordQuery object. I have tried with all the overloaded method for KeywordQuery in SharePoint 2013.  I am able to create SPSite object.

 

Below is the code:

 

using (SPSite site = new SPSite(url))

{

SearchServiceApplicationProxy proxy = (SearchServiceApplicationProxy)SearchServiceApplicationProxy.GetProxy(SPServiceContext.GetContext(site));

using (KeywordQuery keywordQuery = new KeywordQuery(site))//Unauthorised Access Exception on this line

{

//doing something with KeywordQuery object

}

}