Ring Buffer Not Working on OS X

Hello All, Using Wireshark 2.0, setting up a ring buffer where x number of files are used to store the captured frames at y size is not working for me. OS X El Capitan 10.11.1.

In Capture options I set it up as follows:

I have tried with just the file name and also with a full directory path. Tried using the Browse button to select the full path as well. When I try to capture I see the following error:

Verified that the folder used for the test has standard permissions. Changed to full read/write/execute which had no effect on the test.

Anyone else run into this?

Thanks in advance, James