Casting Error

[tikki]

    Sub GetTotal()
        Dim value As Double

        value = 0.0

        OleDbCommand1.Connection.Open()
        OleDbCommand1.CommandType = CommandType.Text
        OleDbCommand1.CommandText = "SELECT SUM(amount) FROM cody"

         Put the total amount into a variable.
        value = OleDbCommand1.ExecuteScalar()
        lblTotalAmount.Text = Value
        OleDbCommand1.Connection.Close()
    End Sub

error:
An unhandled exception of type System.InvalidCastException occurred in microsoft.visualbasic.dll

Additional information: Cast from type DBNull to type Double is not valid.

Help is appreciated. This is my final bug and it just popped up