PHPExcel在主页面显示垃圾

I need to generate a PDF file with some information i get from a database, i'm using PHPExcel in order to do this, but here is the thing, when i click the button `report` so i get all the information and put it into the PDF, i get a lot of "garbage" in my page, this garbage it's like when you try to open a PDF with notepad and it just shows random symbols. I need to generate a PDF file with some inform