listbox controlsource problem

Hi!
sorry my english. I have a problem.
I have a mainform and a subform on it.
I want to create a listbox in the mainform and when i select an item from the listbox, put the selected item into a field in subform.

i do this:

when i put some fieldname from the mainform in sourcecontrol of the listbox , works fine, but when i put a subform field in the sourcecontrol of the listbox, nothing happen.

the controlsource that i wrote is:
Forms![main form name]![subform control name].Form![control name]


can anybody helpme?

thanks for your time guys!

An item in a list box is not referenced the way you are doing it.

Search Access Help for listbox, it shows how to do it.

Filter the subform recordsource with the listbox value, it's not a control.