Matrix() does not operate in place. Again as a convention, functions that do operate in place or change their arguments are denoted by an ! at the end (this is just a naming convention, so you couldn’t just add a ! to some function to make it in-place).
You need to do
PHL = Matrix(PHL)
as in my example above.
I would encourage you to read the Julia documentation to familiarise yourself with the basics of the language.