Soi or soi-même?

I apologize, here is the question: An A2 question asks the french translation of "One must always look in front of oneself." I responded with "Il faut toujours regarder devant soi-même," and it was marked as incorrect. The correct answer was "Il faut toujours regarder devant soi." I am confused why one would not use "soi-même" for "oneself" in this instance.

I think its because you need a stress pronoun after a preposition such as devant rather than stress+même.

Aurélie and Laura have answered this very same question asked by a later poster. 

-- Chris.