SendKeys

Hi

From Excel I want to activate another window and then send some keystrokes to that window.

From the code below:
1) the window "destination.txt" ALWAYS comes into focus reliably (becomes active) - this does not seem to be a problem.
2) the sent keystrokes are VERY intermittent - sometimes they arrive but mostly nothing goes to the "destination.txt" window.

Private Sub Worksheet_Change(ByVal target As Range)
If Range("a1") = "1" Then
    AppActivate "destination.txt"
    SendKeys "one", True
ElseIf Range("a1") = "2" Then
    AppActivate "destination.txt"
    SendKeys "Two", True
End If
End Sub

Any suggestions??