PagedDataSource, ArrayList, Repeater, Objects

[Guest]

I declare a PagedDataSource and make its data source be a arraylist that
contains objects that I've created myself. Then I bind a Repeater with this
PagedDataSource and an error occurs. The following is the error:

Index was out of range. Must be non-negative and less than the size of the
collection. Parameter name: index
Description: An unhandled exception occurred during the execution of the
current web request. Please review the stack trace for more information about
the error and where it originated in the code.

Exception Details: System.ArgumentOutOfRangeException: Index was out of
range. Must be non-negative and less than the size of the collection.
Parameter name: index

Does anyone know why? Thank you in advance.