i had an error with cheat in fallout 3 ... it's all in this pic

[IMG]http://i54.tinypic.com/21npojt.jpg[/IMG]

You need the base actor code to make it work. You don't use the <> in the code. You also need a switch at the end...zero for off, one for on.

setessential a71 1

That would be the correct syntax assuming you wanted to make a character whose base object has an id of 00000a71 essential.

If the character is standing in front of you, click on them in the console and type getbaseobject. That will return a new code. Use the setessential command on them.