主题：vba 保存为PDF求助

Sub aaa()
Dim sht As Worksheet

For Each sht In Worksheets

Dim str As String
str = ActiveWorkbook.Path & "\pda°ü\" & sht.Name & ".pdf"
    sht.ExportAsFixedFormat Type:=xlTypePDF, Filename:=str, Quality:=xlQualityStandard, _
        IncludeDocProperties:=True, IgnorePrintAreas:=False, OpenAfterPublish:= _
        False
Next
End Sub

在excel 运行的  

运行到这段时   sht.ExportAsFixedFormat Type:=xlTypePDF, Filename:=str, Quality:=xlQualityStandard, _
        IncludeDocProperties:=True, IgnorePrintAreas:=False, OpenAfterPublish:= _
        False

提示 运行错误5   无效过程 或者参数。

老师 我修改了一下  想 一个 sheet 保存为 1个 pdf

这样该了

Dim App As New MSExcel.Application
try  
    Dim Wb As MSExcel.WorkBook = App.WorkBooks.Open("C:\Users\user\Desktop\a.xls")
    '创建Excel文件对应的PDF文件
    wb.Saved = True
Dim Ws As MSExcel.WorkSheet
For Each   ws In wb.worksheets 
    Dim str As String  = ws.name
    ws.ExportAsFixedFormat(MSExcel.XlFixedFormatType.xlTypePDF, "d:\test\" & str & ".pdf", MsExcel.XlFixedFormatQuality.xlQualityStandard, True, True,  System.Reflection.Missing.Value,  System.Reflection.Missing.Value, False,  System.Reflection.Missing.Value)
Next
   app.quit
catch ex As exception
    msgbox(ex.message)
    app.quit
End try

但不对 ， 该如何操作呢？