Spawning an Actor Problem.

I am doing another project which involves spawning blocks randomly to make a tower, but for some reason they keep spawning all over the place, and they multiply like crazy.

I have set them on 'When Created.'
It's a Scene behavior.
It has a fair spawning time.

Can anyone please help me with this problem?

To be clear, according to your post you have 2 issues with your behavior that you're trying to fix. There will be more information needed to answer those questions.
1. Blocks spawn "all over the place" : where or in what area do you want them to spawn specifically?
2. They "multiply like crazy" : How frequently do you want them to spawn (X per second, minute? One every Y seconds?)

If you can show us the behavior you are using to spawn them, we'll take a look. Until then, there's not enough information to go on.

1) They just multiply too often. That's what I meant.
2) They spawn about every 0.5 seconds.

So you want them to spawn every .5 seconds - or they currently do and that's undesired?

Can we see the behavior? A lot depends on how you set it up.

Sure Thing! (It's actually 1 second, not 0.5)

I don't see a problem. Now if this is actually an actor behavior attached to the very same actor - yes they will multiply exponentially. But if this is a scene behavior as you say, I see no problem with it according to what you've said.

Strange.

In my previous game, It's Raining Crates, it worked perfectly fine, even after the update of Stencyl 2.0.

Could that be a factor?

Also, I want other blocks spawn like the original. Would those affect the performance of the original block.

You'll have a performance loss with large numbers of actors, but given how quickly they move offscreen and that you only have around 1 per second, then you shouldn't have much of a performance issue.

The update shouldn't have affected it, no. At least in no way that I'm familiar with.