Overflow at 6

Private Sub Command1_Click()
Dim i As Integer
Dim s As String
For i = Val(Text1.Text) To Val(Text2.Text)
s = s & i & vbCrLf
Next i
Text3.Text = s
End Sub


causes an overflow at 6 numbers. my app will need to run 11 max. it will be generating numbers between a set of 11:

ex:

12345670000
12345679999

VB Code:

Dim i As Double
Dim s As String
For i = CDbl(Text1.Text) To CDbl(Text2.Text)
    s = s & i & vbCrLf
Next i
Text3.Text = s