How to query data for CQWP from Visual Studio?

I have added a CQWP from visual studio successfully, now I want to fetch the name of all documents from the library named "Sample Docs".

My code is as below :

 SPSite site = new SPSite("http://bipc11:1234/sites/publishing1");
 SPWeb web = site.RootWeb;
 web.AllowUnsafeUpdates = true;
 SPLimitedWebPartManager webParts = web.GetLimitedWebPartManager("SiteAssets/webparts.aspx", System.Web.UI.WebControls.WebParts.PersonalizationScope.Shared);
 ContentByQueryWebPart wp = new ContentByQueryWebPart();
 wp.Title = "My web part using OM";
 wp.ListUrl = web.Url + "/Sample Docs";
 wp.ListName = "Sample Docs";
 wp.XslLink = web.Url + "/Style Library/XSL Style Sheets/ItemStyle.xsl";
 wp.QueryOverride = "<where> <Eq> <FileRef Name=\"FileLeafRef\" /> <Value Type='Text'/>Sample Docs</Eq></Where>";
 webParts.AddWebPart(wp, "Right", 0);
 webParts.SaveChanges(wp);
 web.Update();
 Console.WriteLine("Web part added successfully");
 Console.ReadKey();

Web part gets inserted successfully but with error, that there is a problem with query...

What should I do? Please help.