"A blank screen" might be caused by your web browser not accepting a missing tag in your HTML. It tells you hardly anything about the problem.
Most web-servers have error logs, look at the logs for yours to see if it tells you anything useful.
Alternatively, running the program from the command line and looking at the output usually helps me.
If that doesn't help, post the code for both files here, so we can see what's wrong.
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