[2008] Arithmetic operation resulted in an overflow

[perito]

When the loop is
For x = 3 to 10
the codes work fine

when i change it to 100, the code gives an eroor
"Arithmetic operation resulted in an overflow."
on the line "If (Result + PreResult) Mod 2 = 0 Then y = y + Result + PreResult"

WHY????

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim x As Integer, Result As Long, PreResult As Long, oldresult As Long
        Dim y As Long
        Result = 2
        PreResult = 1
        y = 3
        For x = 3 To 100
            If (Result + PreResult) Mod 2 = 0 Then y = y + Result + PreResult
            oldresult = PreResult
            PreResult = Result
            Result = Result + oldresult
        Next
        TextBox1.Text = y
    End Sub