Error: Call to a member function on a non-object

That would mean that the $duration variable does not contain an object, which is strange because there are two possible cases due to the if-condition that leads to line 58:

• The first case ensures that $duration is an object. So that can't be it.
• If $duration is not an object, duration_create() is called to assign a new Duration object to that variable. Which should in turn always return an object too, as can be seen at the top of duration.inc.

I have no idea how there can ever be a non-object for $duration on line 58. For the lack of other pointers... which PHP version are you using?

Title change.

PHP 4... ouch. With object handling completely reworked in PHP 5, I guess there's just some incompatibility there, and I don't intend to downgrade to PHP 4 just to support a PHP version that is already unsupported by upstream for nearly a year. If you can fix the cause of the error by yourself, I might be willing to incorporate your patch... otherwise, with PHP 4 as the suspected villain, this is a "won't fix". Sorry.

Leaving this issue open as a pointer to include a PHP 5 requirement in the info files.