Hi,
yes, I should have explained better:
projectors set up is different from normal rendering, hence the set material texture doesn't work as is by default, you need to explicitly reference the material you want to change. so drag the material onto the action slot, and that will work.
I have attached a working prefab, so you can see how the action is set up.
warning, changing materials is permanent, so to test this over and over again, set back the material texture to something else and hit play.
bye,
Jean