documentation - Unable to retrieve docs in a specific folder in google docs using c# -

i'm trying retrieve documents in folder in google docs using below function give in api documentation.. still function returning titles of documents , not of particular folder..

public documentsfeed retrievedocsinfolder(documentsservice service, string folder, string email)         {             atomcategory foldercategory = new atomcategory(folder,             new atomuri("http://schemas.google.com/docs/2007/folders/" + email));             querycategory folderquerycategory = new querycategory(foldercategory);             documentslistquery query = new documentslistquery();             query.categories.add(folderquerycategory);             query.categoryqueriesasparameter = true;             return service.query(query);         } 

try following code:

public documentsfeed retrievedocsinfolder(documentsservice service, string folder) {     string uri = string.format(documentslistquery.foldersuritemplate, folder);     documentslistquery query = new documentslistquery(uri);     return service.query(query); } 

i'm assuming folder resource id of folder want retrieve content for.