diff --git a/ExcelMerge/Entrance.cs b/ExcelMerge/Entrance.cs
index f958bc0..d1f7859 100644
--- a/ExcelMerge/Entrance.cs
+++ b/ExcelMerge/Entrance.cs
@@ -74,11 +74,11 @@ public static void OnDragFile(string[] files, bool isSrc)
                     {
                         if (isSrc)
                         {
-                            SrcFile = files[1];
+                            DstFile = files[1];
                         }
                         else
                         {
-                            DstFile = files[1];
+                            SrcFile = files[1];
                         }
                     }
 
diff --git a/ExcelMerge/MainWindow.xaml.cs b/ExcelMerge/MainWindow.xaml.cs
index f8e1dc4..a25ddf1 100644
--- a/ExcelMerge/MainWindow.xaml.cs
+++ b/ExcelMerge/MainWindow.xaml.cs
@@ -496,6 +496,10 @@ List<string> GetHeaderStrList(WorkBookWrap wrap, ISheet sheet) {
                     list.Add(row);
                 }
                 
+                if (list.Count == 0)
+                {
+                    return null;
+                }
                 for (int i = startcol; i < list[0].Cells.Count; ++i) {
                     var str = "";
                     for (int j = 0; j < list.Count; ++j) {