It would have helped to specify that, so that we can skip the obvious solutions 
So, which steps and options did you already try?
Secondly, the auto-mount via the webUI does not give a whole lot of feedback I think. Can you try to mount the share via the command line (via SSH) and see which errors are returned?
Just a quick Google search already results in a few options to try from OS X to Raspbian:
superuser.com/questions/1239142 … spberry-pi
reddit.com/r/raspberry_pi/c … e_on_a_pi/