Private Sub cmdEintragen_Click()
Dim iCounter As Integer
For iCounter = 1 To 3
With Controls("TextBox" & iCounter)
If IsNumeric(.Text) = False Then
MsgBox "Bitte Wert in TextBox" & iCounter & " berichtigen!"
.SetFocus
.SelStart = 0
.SelLength = Len(.Text)
Exit Sub
End If
End With
Next iCounter
For iCounter = 1 To 3
Cells(1, iCounter) = CDbl(Controls("TextBox" & iCounter).Text)
Next iCounter
End Sub