Hi,
uhm, that's going to be tricky yes. I would recommand not using Unity GUI for stuff like that, unfortunatly it is possible but requires scripting, and the very design of Unity GUI system makes it difficult to adapt to PlayMaker environment. Unity GUI is a non persistent system, so your code is executed on every pass, and within Playmaker it's not really working this way as you have States and transitions, and you expect elements to persist between states, so it's very much conflicting here.
Try using GuiTextures or a complete 2d framework like 2d toolkit or nGui.
bye,
Jean