Appended row not being displayed

["Ohrnberger, Erik" <erik_ohrnberger dme net>]

I've got a bit of a mystery here and am hoping that you can help me out.  I'm appending a number of rows to a treeview's model, but don't see them in the user interface.  The list is sorted by a gulong column that is not visible to the user.

I've added debug print statements to my code, and I can see by their output that the values are really being put into the appended row.

Has anyone experienced anything like this?  
Is there a method on the TreeView that can make sure that all the rows are displayed?
Is there a TreeView method that would force an update of the graphical rendering, should something like be needed?

I have to admit that I'm stumped on this one.

I should note that I'm using gtkmm-2.4.8

Thanks in advance.