Focus failure

Hi. I hope you can help. I've a canon 40D and am using it remotely with the EOS utility v 2.3. I am only able to take an image when the live view mode is active. When inactive and I use either the shoot button or the timer, an error flashes up "focus failure". The camera focuses fine in live mode.

Have dragged my way through the instruction manual and cannot find a troubleshooting section covering this problem.

Hope you can help.

Thanks

Joe