Update: Sadly this doesn’t work. Ok I really need to fix this bug soon.
Getting this message from DIYPhotobits.com Camera Control when you click the “Shutter Release” button?
It’s a bug, the script is failing to handle the fact that the camera is very slightly slow in delivering the image after taking it.
To avoid this:
Stop using the “Download Immediately” checkbox
Instead, press the “Start Tether” button.
The result is (almost) the same; when you click Shutter Release the images ARE immediately downloaded (because the tether is running), but it’s by a different piece of code that patiently waits for the image to become available rather than demanding it immediately.