Randomly pick 1/3 box sprites as a trigger

I have 3 sprites at start of layout - called 'box' - 32x32 in size.

system = create object box on layout 0 at (16,17)

system = create object box on layout 0 at (box+32,17)

system = create object box on layout 0 at (box+32,17)

I'm trying to randomly nominate 1 of 3 boxes to be a trap door. so if 'platform' player collides, the trigger will spring.

I've tried 'Pick a random box instance' with another object, but it just ain't working out.

poor example - sorry

____ ____ ____

| | | | |x |

----- ------- ------

Does this make sense?

I'd appreciate all the help I can get.

Roberto

something like this some work.

system = create object box on layout 0 at (16,17), set instance variable = 1

system = create object box on layout 0 at (box+32,17), set instance variable = 2

system = create object box on layout 0 at (box+32,17), set instance variable = 3

on start of layout(or whatever) >>> set global variable to floor(random(1,4))

then system pick by comparison to select the block that has the same instance variable as the random global.