Ok, i've stupid question about bluescreen effect. I have two clips including one with blue background. Clip what I wanted to add instead of bluebox went on track 0. Clip with bluebox went on track 1. To "bluebox clip" ("background clip" will be a clip which eventually go instead of bluescreen) i added Blue Screen video effect. Unfortunately I have still blue background instead of fancy one. I tried even to use composite transition, but it didn't work. How to use it properly?
//EDIT: Additionally I saw that when I set Variable (this track bar with blue screen effect) to 100 percent the bluebox clip completely disapeares. Of course i want only to hide blue parts of clip so I don't know what to do.