user control inside a repeater - problem passing data table through a property

I have a user control inside a repeater. I set a property of the usercontrol
in each repeater data item. This property is used to display the data inside
the user control.

This structure works fine. However when I send a datatable through this
property I end up loosing the data table reference when an event is fired
inside the user control. I am able to store the datatable into viewstate and
use it from there when I need but this is not an efficient approach since I
store a very large data on client and increase the download times.

I can't find why my reference becomes null when an event is fired, in the
case I pass a data table / data row into the user control. Any help is much
appreciated..

Thank you