note that unset() works well for associative arrays, but if you have
$blah = array("a","b","c","d");
and you unset($blah[2]), then the other
elements will not shift, i.e., you'll still have $blah[0], $blah[1], and $blah[3]. If you need things to shift, use
array_splice($blah,2,1);
In your case try:
array_splice($aItem, 3, 1);