zsh autocompletition on alias not working

Question

I have written this simple autocompletition function for my script:

alias activate=". ~/.activate.sh"
_activate() { _files -W ~/Projects; }
compdef _activate activate

It works if I comment out the alias-line, but otherwise I get the following autocompletition:

activate P
Pictures/  Projects/  Public/

Answer 1

The solution was quite simple, adding the following to my .zshrc solved the problem:

setopt complete_aliases