sounds like you're dual-boxing.

one thing about the case sequence macro is that its illogical. you dont need a cast sequence in order to cast the same spell over and over and over. whoever made that macro probably was not thinking.

there are three common ways to help target what your main is targeting. reeally quick, here's the lowodwn on the three.

1. assist. when using assist, your slave actually switches target from targeting your main, or whatever else he is targeting, to the target your main is targeting.
your macro would work with a cash sequence, and Golle's macro would work as well.

2. focus. if you make a macro, or just type /focus when your slave is targeting your main, you will have a focus for the rest of the time logged in. using "target=focustarget" will alwyas target whatever you main is targeting, that's IF your main is the focus.

3. targettarget. this is basically part of the macro that says, target my target's target and cast whatever spell is in this macro. this requres that your slaves always target your main, after looting, after combat, after dialogs with npcs, etc. slaves will lose the main as a target all the time, so having a macro that will target the main, plus follow the main, is essential to this setup.

as for the PW:Fort buff, i'd like to add another thing to it to make it target yourself:
/cast [mod:alt, target=player] [target=party] Power Word: Fortitude