I have set-up three variables in the images/controls/variables folder named 'curtains_status.png', 'curtains_status+closed.png' and 'curtains_status+open.png'. I have defined the field to 'Display Variable Value', selected the variable to be tested which can have a value of 'open' or 'closed' and selected the image in the pull-down as 'curtains_status.png'. It shows correctly in the Control Page editor (indicating it has picked up the image) but when I do a Browser Preview the image is blank.
If I change the variable to '- no value -' the image displays, as it does if I change the value to 'false'. It almost seems like the value of the variable is being ignored. Probably something I am doing but can't see it at the moment.
