Extra TAB in front of all of HTML or xml output

There is TAB in front of all of HTML or XML view output in my Yii.


	<?xml version="1.0" encoding="UTF-8"?>

<rss xmlns:content="http://purl.org/rss/1.0/modules/content/" version="2.0">


	<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">

This tab caused me a XML error:

Invalid xml declaration.

 Line: 1 Character: 4

 <?xml version="1.0" encoding="UTF-8"?>

I don’t find any TAB in Yii webpage source. Please tell me how to remove it.

Perhaps remove any PHP closing tags you may have added at the bottom of PHP files? Or at least remove any excess data.