I can't seem to get the modelling light active on more than one unit at a time, using one Master and one remote, for example. I notice that on the back of the Master unit, if the Master is highlighted when I hit the modelling light button, the Master unit does its thing but not the remote. If the Remote is hightlighted on the Master unit's LCD, the Remote does its thing but not the Master. A lot of good that does! Am I suppose to guess by superimposing my two memories? Here's the thing - when I put both units in SU-4 mode, pressing the modelling light button on the unit which is connected to the camera will actually cause both units to activate the modelling light (although pressing this button on the stand-alone unit does nothing). This would be fine, except that I can't run between both units switching between SU-4 and the other wireless modes every time I need the modelling lights (because you cannot remotely control a remote unit in SU-4 mode, or use any of the other CLS features). I can't believe it's suppose to work this way, and the manual does appear to say all the modelling lights should fire together. What is going on? Thanks.