So I'm having issues with vampire transformations

So I heard that on Sims 2 Pets (I think)
you can change your sims into a vampire with the boolprop cheat, yes?
On my game, I have that option but it doesn't change them D:

I also have Sims 2 University and Sims 2 and Sims 2 Holiday Deluxe.
Could one of those games be interfering with the vampire transformation?

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I have tried playing my Pets game on my friend's laptop,
which she has Sims 2 Night Life
and they can change into vampires; do I need Night Life for them to change?

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I would love it if I could get help right away; I love vampires (not Twilight, thanks)
and I would love it even more if I were able to change my sims into vampires ; -;