Forcing Domain OU selection in SCCM 2012 R2 UDI

Question

We have added various domain OU to our UDI so that a newly imaged machine will join the correct OU during imaging. However, I can't figure out how to make OU selection required. When left as the default, it will select the top OU in the list. I've added
a blank line at the top with "Make a selection" as the "Friendly name". If someone does not select an OU (leaving it on "Make a selection") the computer will join the domain Computers OU. 

Answer 1

Okay - I am on the same page as you now.
Create a OU (manually) like this:
Friendly Name: Please select an OU
DN: Sel=domain.com
And then create an validator using a regular expression (RegEx) using this
^(ou=) as the regular expression.
I have not tested this but it should work
Thanks for the info. However, either I didn't understand, or this may not work. Here is what I've done:
When I try to save the file I get the same error that I was getting in the screenshot of my previous reply:
The element 'Field' has invalid child element 'Default'. List of possible elements expected: 'Validator'.
As you can see above I tried putting in a default value, however, it also gives the same error when I leave the default value blank. Before adding this regex validator the default value was left blank, and I didn't receive this error. This error only occurs
when I try to add a validator and save the file.