Custom header image with error

I am using wordpress 3.5 and twentyten theme. I have brought in some changes in the theme through using child theme. In order to change the header image size I used functions.php file with the following code.

<?php

function tnc_header_width($width) {
$width =980;
return $width;

function tnc_header_height($height) {
$height = 224;
return $height;

}

}
add_filter( ‘twentyten_header_image_width’, ‘tnc_header_width’);
add_filter( ‘twentyten_header_image_height’, ‘tnc_header_height’);

?>

It worked. But in the front end I am getting the following message

Warning: call_user_func_array() expects parameter 1 to be a valid callback, function ‘tnc_header_height’ not found or invalid function name in C:\xampp\htdocs\wordpress\wp-includes\plugin.php on line 173

How can I remove the message? I opened plugin.php file, but I could not solve the problem. Please help me.