multidimensional array sorting

I am trying to sort a multidimensional array but it doesn't seem to do anything. I have an array that stores the dates broken up into month,day, year format. And I want to sort the array based on the day. This is the way I was trying to do the sort. I am trying to compare the second elements in the lines to sort the array. For some reason it doesn't change the order of the array at all. Am I missing a step here? usort($lines,compare); function compare($x,$y) { If ($x[1] == $y[1]) return 0; else If ($x[1] < $y[1]) return -1; else return 1; } Kelly