BoxHeights.equalise(,'c4'); error on Template

<script type="text/javascript"> <?php $cUserArray = Array(); $cAdvArray = Array(); if($showuser[5]) $cUserArray[1] = "'c1'"; if($showuser[6]) $cUserArray[2] = "'c2'"; if($showuser[7]) $cUserArray[3] = "'c3'"; if($showuser[8]) $cUserArray[4] = "'c4'"; if($showadvert[1]) $cAdvArray[1] = "'c5'"; if($showadvert[2]) $cAdvArray[2] = "'c6'"; if($showadvert[3]) $cAdvArray[3] = "'c7'"; if($showadvert[4]) $cAdvArray[4] = "'c8'"; ?> window.onload = function() { <?php if($bottommodules) { ?> BoxHeights.equalise(<?php echo join(",",$cUserArray); ?>); <?php } ?> <?php if($uppermodules) { ?> BoxHeights.equalise(<?php echo join(",",$cAdvArray); ?>); <?php } ?> } </script>