public Declare Function MessageBox Lib "user32.dll" Alias "MessageBoxA" (ByVal hWnd As Long, ByVal lpText As String,ByVal uType As Long) As Long

'OKボタンを保有するフラグ
Public Const MB_OK = &H0

'最前面フラグ
Public Const MB_TOPMOST = &H40000

'呼び出し
Public Sub TestTopMostMsgBox()

Dim lpText As String
Dim lpCaption As String

lpText = "テスト"

MessageBox 0, lpText, lpCaption, MB_OK Or MB_TOPMOST

End Sub

これを実行すると必ずexcelが落ちるのですが何がいけないのでしょうか・・