This message is generated when either the fourth argument or the fifth argument in a SeriesData expression is not an integer or is an integer that cannot be represented as a machine integer on your computer.
Off[message] switches off the message; On[message] switches it on. For example: Off[SeriesData::sdatn].
Examples
Basic Examples(1)
An error occurs because a list is not a valid value for the fifth argument in SeriesData: