使用delphi xe3在MSWord页眉和页脚中搜索和替换

我想在单词的页眉和页脚中搜索特定的单词，然后将其替换为数据库中的单词.

I would like to search in a word header and footer for specific words, and then replace them with words from my database.

当前，我可以在word文档中的任何位置搜索和替换单词，但页眉和页脚除外.

Currently i can search and replace words anywhere in the word document except for the header and footer.

有人可以帮我吗?

正常搜索的代码(有效):

Code for normal search(that works):

Procedure FindAndReplace(Find,Replace:String);
Begin
      //Initialize parameters
  WrdApp.Selection.Find.ClearFormatting;
  WrdApp.Selection.Find.Text := Find;
  WrdApp.Selection.Find.Replacement.Text := Replace;
  WrdApp.Selection.Find.Forward := True;
  WrdApp.Selection.Find.Wrap := wdFindContinue;
  WrdApp.Selection.Find.Format := False;
  WrdApp.Selection.Find.MatchCase :=  False;
  WrdApp.Selection.Find.MatchWholeWord := wrfMatchCase in Flags;
  WrdApp.Selection.Find.MatchWildcards :=wrfMatchWildcards in Flags;
  WrdApp.Selection.Find.MatchSoundsLike := False;
  WrdApp.Selection.Find.MatchAllWordForms := False;
     { Perform the search}
  if wrfReplaceAll in Flags then
   WrdApp.Selection.Find.Execute(Replace := wdReplaceAll)
  else
   WrdApp.Selection.Find.Execute(Replace := wdReplaceOne);
End;

页眉和页脚搜索的代码(无效):

Code for header and footer search(doesnt work):

WrdApp.Selection.Find.ClearFormatting;
      WrdApp.Selection.Find.Text := 'Class';
      WrdApp.Selection.Find.Replacement.Text := grade;
      WrdApp.Selection.Find.Forward := True;
      WrdApp.Selection.Find.Wrap := wdFindContinue;
      WrdApp.Selection.Find.Format := False;
      WrdApp.Selection.Find.MatchCase :=  False;
      WrdApp.Selection.Find.MatchWholeWord := wrfMatchCase in Flags;
      WrdApp.Selection.Find.MatchWildcards :=wrfMatchWildcards in Flags;
      WrdApp.Selection.Find.MatchSoundsLike := False;
      WrdApp.Selection.Find.MatchAllWordForms := False;
     { Perform the search}
  if wrfReplaceAll in Flags then
    WrdApp.ActiveDocument.Sections.Item(1).Headers.Item(wdHeaderFooterPrimary).Range.Find.Execute(Replace := wdReplaceAll)
  else
    WrdApp.ActiveDocument.Sections.Item(1).Headers.Item(wdHeaderFooterPrimary).Range.Find.Execute(Replace := wdReplaceOne);