You need to set the ExcludedFileAttributes property to xfaNone. Here is a code example:
XceedZip zip = new XceedZipLib.XceedZipClass();
bool licenseResult = zip.License( "License key" );
Console.WriteLine( licenseResult.ToString() );
zip.PreservePaths = true;
zip.ZipFilename = @"D:\Forum11694\archive.zip";
zip.FilesToProcess = @"D:\TestFolder\*";
zip.ProcessSubfolders = true;
zip.ExcludedFileAttributes = xcdFileAttributes.xfaNone;
xcdError message = zip.Zip();
Console.WriteLine( message.ToString() + " (" + ( ( int )message ).ToString() + "):" );
Console.WriteLine( zip.GetErrorDescription( xcdValueType.xvtError, ( int )message ) );
Charles Bérubé-Rémillard
Technical Support
Xceed Software Inc.