php + javascript help

hey /g/ i have a question about web coding.
im using php and javascript to output a grid of thumbnails which when clicked upon will load a larger version of the image in another part of the page. the thumbnail load, i can get an image to change, but for some reason the thumbnails wont load the larger image. here's the code i have:

<SCRIPT LANGUAGE ="JavaScript">
function clicky(f)
{
active.src=("images/environments/"+f);
}
</SCRIPT>

<?php
$i=0;
$filenames=scandir("images/environments");//puts filenames into an array
foreach($filenames as $file)//somehow goes through the array and...
{
if(!($file == '.' or $file == '..'))
{
if($i==2)
{
echo '<br>';
$i=0;
}
echo '<img src="images/thumbs/t'.$file.'" onclick="clicky('.$file.')">';
$i++;
}
}
?>

and later in the page, the large image that should change:

<img name="active" src ="images/environments/Giraffetapus.jpg">

any idea what the heck is wrong with it?
basically, im tying to figure out why, when i click on the thumbnails, the image dosent change. i think its in either the cilcky() function or the onclick event

What fucking year is this. Is it 1998? Why the fuck do you have code in your markup. And why is that code directly echoing static markup directly to the page.

And what is with that markup. It must be 98. Your line break and image elements are poorly formed.