Blank PDFs from a view

Blank PDFs from a view

I have developed an application which has a feature which allows the user to download or print an invoice. It simply is a view which they can print or create a PDF. The PDF creation is the problem. When they click on PDF they receive a blank PDF in their viewer of choice. Occassionally though this does work??? The printing works fine. Why are they getting blank pages?? Is there a timer involved???