Trouble with Adobe After Effects

[RearAdmiral]

I have been following this Link's video tutorial on how to make light sabers in after effects, now I can get everything to work except for the part where the lightsaber must be screened to my video. When I hit screen, nothing happens, as opposed to this video. Are there any ideas on what went wrong. I am using after effects 6.5 and transfer modes are now called blending modes, which i assume is the same thing. Any ideas?