Cannot modify header information

I am trying to widgetize the theme fspring. I didn’t have a functions.php file, so I created it and put in the following code.

<?php
if ( function_exists(‘register_sidebar’) )
register_sidebar();
?>

After adding the sections of code to the sidebar, the widgets worked fine. But I am now getting a “Cannot modify header information” error very frequently. I understand that this means that there is excess whitespace in one of my files.

wp-content/themes/fspring/functions.php:1)

I looked at line one in my functions.php file, but the only thing on that line is

<?php

I tried the technique of holding backspace between the < and the ?, but that didn’t work.

I am absolutely flabbergasted. I have tried everything mentioned on any threads I could find about this, but to no avail.

Does anyone have any idea what is wrong?