I've not really used the yes-no variables in EPDM, have you tried writing 0 or 1 instead to see if that works?
I would set the ProE variable to string ('yes' or '1') instead of a runtime variable. If you do that the first two lines can be removed. After the 'For all documents', add in Check out file (%Path of selected file%) and after set variables check in file (%path to selected file%).
works like a champ.....thanks.