Row that is added directly to the DOM via Ajax gets deleted when fnAdjustColumnSizing is called

I have a ASP MVC Ajax link, that adds a tr to the tbody element of the table.
1. The dataTable does not seem to notice this as the empty-message is still shown.
2. When i call fnAdjustColumnSizing the newly added tr gets removed from the dom.

How can i tell the dataTable that a new row has been added to the dom and make it recognize it as valid row?