Vector in Component Form

I am trying to write in component form, using usepackage{amsmath}, usepackage{amssymb} and usepackage{amsbsy}. When I write vij, there seems to be a mistake and the following appears. I downloaded an environments package online and I manage to write vectors in other forms quite well. If anyone could please advise where I went wrong it would be great!

FYI, the environments package include the following:

and

usepackage{ifthen,xstring}