animation; please help!

I have replied to this in the Pro forum.

Richard

I want to build just a blinking signal, just on and off. When in animation mode I texture-map the signals panel then turn to the next step, use the update function and apply the panel again with light. The result is when I play the animation that the first panel is pushed to the left and the second, the lighted version is pulled in andnbsp;from the right, presumably because they are part of one texture-file. How do I get the effect of real blinking i.e. simple and fast exchange of the texture-maps? Do I have to use 2 different texture maps?