Combobox Reference Showing Up As Parameter

I made a form that has a combobox that references the combo box above it, and it all worked fine, then I moved it into a navigation form and it stopped working. This was because the source was still using the static reference of the standalone form, not the subform it is now. So I've changed the row source a number of times, but each time, when run, access fails to find it, instead asking for a parameter to be input. The lines

The Nav form is Navigation_Form, the subform is MCR_Log, the combo box is Affected_Subservices and the referenced combobox is Affected_Services.

Code:
Forms!Navigation_Form!MCR_Log.Form!Affected_Services
or
Code:
Me!Affected_Services

does not work, even if I change the bangs and dots around. I can't attach the file to this forum, so here is a dropbox link to have a play around.

Bonus Question, I want the first combobox to accept multiple arguments, and the second to display all the subservices under each service, would the record source for that look something like

Code:
SELECT Subservices.Subservice FROM Subservices WHERE Subservices.Parent = Me!*Affected_Services*;
?