DateTime method chaining problem

Question

This works:

$aWeekAfterDate = new DateTime(); 
$aWeekAfterDate->modify('+1 week');
$aWeekAfterDate->format('d.m.Y');

But this:

$aWeekAfterDate = new DateTime(); 
$aWeekAfterDate->modify('+1 week')->format('d.m.Y');

Gives me this error:

Fatal error: Call to a member function format() on a non-object in ... on line ...

Fatal error (shutdown): Call to a member function format() on a non-object in ... on line ...

I have looked up the DateTime::modify method in the documentation and its return value is this:

Returns the DateTime object for method chaining or FALSE on failure.

Why is method chaining not working?

I am using PHP version 5.2.6.

Answer 1

Changelog

Version   Description 
5.3.0     Changed the return value on success from NULL to DateTime. 

So returning the DateTime object for chaining was only introduced in PHP 5.3.0