Problems with Skewers

Hi, I really enjoy the videos on the site!

Quick question for you. I was attempting to make some skewers on the grill recently and I used chicken. Since I am afraid of food poisioning I checked the meat and I realised that the chicken wasn't cooked throughout. The problem is that the other vegetables on the skewers were cooked perfectly and had I left the skewers on there longer they would have all burnt.

What can I do to prevent this.

Thanks!