I assume you expect what you type in the Combobox should be stored into the rowsource. That's not happening.
Every control saves to it's controlsource (the grid is an exception, but within it, the columns all maintain their controlsource, too).
As you see the Combobox has two data sources. The data source to define its items is the rowsource. The controlsource both determines what item is picked and where the picked item or entered text is saved.
The entered text becomes the value of the combobox, just like the picked item text. Unless you bind the controlsource to an integer foreign key field, that won't work with a dropdown combo style combobox.
Anyway, the combobox never maintains the items. You can have a textbox with autocomplete feature, if you want that. Or program the adding of items yourself.
Bye, Olaf.