I'm still working with the theory it's your phone, so if there's >1 seeing this, ignore the following.
Sometimes phones need to really be wapped upside the head. First delete the original download (you may need a file manager to do that) Then power down, and remove the battery for at least 30 seconds..on power up, re-install the app from the ZD and try again.
If that still doesn't work...open a support case, but if we can't reproduce it, we'll probably direct you to Samsung. I am not finding any similar cases open with us at the moment. (and I personally use an S4 and didn't have any trouble last time I loaded zero-it)
Also...is the SSID you are trying to connect to (the final one) broadcast? (visible) Android recently followed Apple's lead in dis-allowing automated connections to hidden SSID's