Debug and Fix an existing PHP Excel Export Function

This is not a large project, please bid accordingly. It's a simple project to FIX functionality for an existing script. I have report written that displays a result set directly on the page, I paid someone else to add a function that exports the results to "Excel". The function worked fine for many months, and then stopped working. When "Export Excel" is clicked, now you get logged out instead of the results getting exported to Excel. I simply need someone to debug and find out why the function isn't working and fix it. Here is a screenshot of the existing data displayed on the report page; [login to view URL]