I Don't Understand How This Isn't The Answer

Hi, could anyone explain to me what this question is actually asking? I've done what the question wants, and it won't pass, or tell me why it's not passing.

The Question: When saving a date in a 'date' field, you need make sure the date is formatted properly. The correct format is YYYY-MM-DD.

Complete the function to convert a passed date into a SQL safe date and return the results using the following requirements:

Use the date() function to properly format the passed date. Use the strtotime() function to accept anything from a date in a different format to a string like 'yesterday'.

My Code: function convert_date_sql($date) { //add your code here
return date('Y/m/d', strtotime($date)); }

<?php

function convert_date_sql($date) {
    //add your code here    
    return date('Y/m/d', strtotime($date));
}