Sharepoint 2010 COM groups silverlight

I'm getting开发者_开发技巧 the groups with:

var GruposSP = web.SiteGroups;
ClientContextLocator.ClientContextHome.Load(GruposSP, groups => (groups.Include(g => g.Users)), groups => (groups.Include(g => g.LoginName)));

And it throws me:

"Access Denied". You do not have permission to perform this action or access this resource

Is there any way to get the users from a site without permission?

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My Solution:

With the next line you get the users and groups from the web

ListItemCollection usersList = ctx.Web.SiteUserInfoList.GetItems(CamlQuery.CreateAllItemsQuery());