First off, if you're trying to make some sort of trail for your bullets, you should use particles instead of plasma. Plasma is much more GPU intensive than particles, and since your bullets are just going to zoom off anyway you won't really see the trail effect. Also, Plasma objects animate within the bounding box so moving them around quickly sort of defeats the purpose. You can make some good trail effects with particles, just play around with them a bit.
Second, you need to TimeDelta your bullets (check the wiki), or use Bullet Behavior. You're moving them at a set number of pixels per tick, and this means that your game will run at different speeds on different machines.
Third, when you have two objects in a container, you only need to create ONE of them... the other one is created automatically. So you can just do this:
- Create object Bullet
[li]Set object BulletTrail position to Bullet[/code:jol23xug][/li]
This will create both the bullet and the trail, and set the trail in the proper place.